Linewide Direction
The central idea would be to take everything that's been good about the past few years of the franchise and strip away everything else. Do away with the whole "dark and gritty" direction that's permeated the series since Civil War (or arguably Disassembled) and staff the books with bombastic, big idea talent. The new series of books would be bright, colorful, and unafraid to be outrageous. Despite the many, many problems I had with Civil War, I think the Fifty State Initiative is a very clever meta way to inject new characters into the universe, which as far as I'm concerned, is the biggest problem faced by the big two comic companies. I've got to admit, I love the idea of major league sports style superteam franchising. We would see second-stringers introduced in these side books moving into more prominent positions on the bigger profile teams. But the current nature of the superhero registration stuff is an albatross hanging around Marvel's neck. Just completely reversing the repercussions of Civil War would be infeasible, so instead we'd see a slow chipping away at the current regulations, over the course of the next few years. Immediately coming out of Siege we'd see Steve Rogers taking a position as the head of the Superhuman Armed Forces, and with it, a tectonic shift in the nature of the registration laws. With the corruption of HAMMER revealed and the resultant harrowing of membership on the various state teams, as well as Rogers serving as a figurehead, it becomes much easier to institute change in the natures of the law. A moratorium is placed on the criminal hunting of unregistered heroes, with the process being readjusted to prioritized unregistered superhumans based on their threat level. The former Captain America stepping up as a figurehead of the national superhuman movement would galvanize a number of high profile superheroes into throwing their support behind the SHF. New superhumans would be required to license themselves and undergo training if they basically wanted to operate with "union" benefits, but active superheroes would essentially get grandfathered in to the organization. Since the Avengers books are basically at a 3.99 price point linewide, Marvel would follow DC's lead and supplement the majority of the books with a back-up feature to justify the price hike. The exception would be the core Avengers book, which would retain a single feature but get an increased page count. The artists on this book would rotate each story, allowing them to highlight their marquee talent, and insuring that, with the increased page count, the book doesn't fall out of schedule.
The Avengers
Story by Ed Brubaker and Matt Fraction, Art by Olivier Coipel, Doug Mahnke, Ivan Reis, Brian Hitch etc. (rotating)
This book would be the masthead for the entire Marvel universe. With Marvel moving away from yearly events, this would become the "event book", with plus-sized 3-6 issue stories, each modeled as an event in its own right, sort of similar to the direction of Grant Morrison's run on Justice League. The new Avengers team would be America's premiere super group, under government jurisdiction, the big guns they send into situations that the Initiative teams aren't strong enough to handle. Captain America (Bucky Barnes), Thor, and Iron Man would serve as the nucleus of the team. Bru and Fraction, as the heavy artillery of Marvel's writing stable, would co-write the book. Just as importantly, these guys hold the monopoly of writing the core books for the three leads, allowing them to seed team events into their solo books and vice versa. Tigra, Gauntlet (both from Initiative), Doctor Voodoo, and Ms. Marvel would round out the core team. But the jurisdiction of the team would allow them to "deputize" any US registered superhero on the team, allowing the writers to highlight specialist background characters and feature team-ups with other Initiative teams as the situation demands. They would be based out of Washington DC, and most of the adventures would be based in the US, with occasional ventures abroad and into other realms. Regardless, the focus would draw away from the centralized NYC focus of the Marvel universe at large. The first bit of stories would deal with them hunting down the war criminals in Osborne's former retinue and redressing the wrongs he committed against the American people.
Avengers New York
Story by Joe Kelly and Fred Van Lente, Art by Gabriele Dell'Otto
Backups by Brian Michael Bendis and Various
The New Avengers would essentially be instituted as the New York team, given the moniker of "Avengers New York" due to New York's close association with the team, but we'd see some major changes in the team line-up. Mockingbird, Ronin, Captain America, and Ms. Marvel would leave the team for greener pastures, although the crossover potential with the core books would leave a lot of potential for these characters to still interact with each other. Danny Rand would come on as the team's private financier and join the team as Iron Fist and he'd be joined by Komodo and Trauma (from the Initiative), Wiccan and Hulkling (from Young Avengers), and Doctor Strange. Luke Cage would keep on as leader, while Jessica Jones would stay on in the background as the sort of team den mother. This would be the New York flavored team book, dealing with local threats. Kelly and Van Lente are the two saving graces of the rebooted Spider-Man book and their quirky, irreverent sense of characterization would make them ideal to take over Bendis' version of the Avengers as a sort of surrogate family. The first arc would deal with the New York Avengers facing off against a rogue Daredevil at the helm of the Hand. They would later square off against a number of the rogue Dark Avengers who have evaded capture following Osborne's fall.
BMB would handle the back-ups, which would feature solo stories of the characters he's leaving behind. Luke Cage, Spider-Woman, Jessica Jones, and Iron Fist would get highlights and possibly lead into some kick-ass Danny/Luke "Heroes for Hire" back-ups further down the line.
Avengers Worldwide
Story by Jeff Parker, Art by Frank Quitely and Stefano Caselli
Ronin and Mockingbird Backup by Andy Diggle and Jock
With the core book and the New York book focusing largely on the Avengers in America, Avengers Worldwide would pick up the international scene. With the US's jurisdiction for deploying superhumans abroad a sticky situation (After all, given all the SNAFUs America has been going through, the international community is surely a little reticent to accept their help), Hank Pym's team are the guys who regularly get called in for international incidents. Comprising largely of the Mighty Avengers membership, who are still wary of the registration laws back home, their team would have more international players, and would serve as contractors for the United Nations and international agency GRAMPA. This book would have a more international cast and draw a large amount of flavor from the run of Justice League International, mixing humor with realistic inter-personal drama. These guys would regularly work hand-in-hand with rarely seen super teams abroad, and retain much of the Mighty Avengers cast, with British hero Blade and Wonder Man added to the mix. Jeff Parker is a wonderful writer who would be a perfect fit. Frank Quitely, who's proven he's great at visualizing new characters (something that would be required for the team-ups with international teams) and large casts would rotate with Stefano Caselli, who would bring a clean, Euro-cartoon flavor to the mix.
Andy Diggle and Jock would provide the back-up, starring Mockingbird and Ronin as international spies directly under the command of the President. Bombastic international intrigue!
Avengers Institute
Story by Geoff Johns, Art by Francis Manapul
Fifty State Initiative Backups by Various
Finally, Johns and Manapul would take over the replacement book for The Initiative, featuring established Marvel characters in authoritative roles training new heroes and young recruits adopting old legacies. Steve Rogers would serve as the school supervisor, with an all-star cast of supporting heroes (War Machine, Doc Samson, Black Widow), and brand new faces. The central idea would be to seed the universe with brand new characters who can later be promoted to positions in the back-up spotlights and mainstream teams. Johns has shown a brilliant knack for ensembles, be it large teams of young characters (Teen Titans), or streamlining the complex legacies of superhero universes (Justice Society of America), both qualities that would be essential for this book; and Francis Manapul has both a great style and a strong talent for portraying young characters, something that a lot of artists seem to have trouble with. Plus, these two guys work magic together.
The back-ups would bring in all-star creators to tell shorter form but still multi-part stories highlighting teams and characters that they either have an associated fondness for, or teams taking places in states that they're greatly familiar with. Matt Fraction could come in to tell a story about the Champions. Warren Ellis could take a guest spot with the Thunderbolts. Slott would serve as the pinch hitter for the backups, given his history with A:TI and a number of the associated teams.