User blog comment:Mark4518/X-Men’ Producer Would Love An ‘Avengers’ Movie Crossover/@comment-1895174-20130219133851/@comment-1895174-20130220034236

Joss Whedon's writing barely handled the large cast in The Avengers. Aside from Iron Man, none of the characters really had an arc, and you'll often find fans of the film debating amongst themselves who got shafted the most (Hawkeye? Thor?). And even then they had to cut a lot from the film, like a cameo appearance from Peggy Carter. I couldn't imagine him handling a cast with the added baggage of the X-Men film universe.

And as to Fantastic Four and X-Men sharing a universe, I still think it's a phenomenally stupid decision. If anything, they could use the Fantastic Four as a launching point for spin-offs. Use the right characters, and a successful Fantastic Four franchise could also lead to Black Panther, Sub-Mariner, and Silver Surfer franchises. Heck, if done right, they could even use it to reboot the X-Men franchise if they don't mind starting off with Onslaught.