And we are really left guessing about the Phoenix after that... She definitely still has the powers, she doesn't know what to make of them, because, as you saw in the ROTK arc, Thor warns her about what the Professor can't understand about her powers, and the answers could very well lie in someone like Shinobi Shaw, White Queen, Selene, or even the Fenris Twins (They could even be the Hellfire Club remains). You never know, but, if they brought back such an organization, it could work without Sebastian and it could work without those no name heads in the actual club. Count Beast out, yes, but not the Hellfire Club.