If I'm not mistaken, MegaBlocks make Marvel toys, so I don't think Lego can do them.
sadly, this is the case. they signed a 10-year deal back in 2004. After it expires, I would love to see a Lego X-Men game. but as things stand now, we usually get a new Lego game after a new series of Legos are introduced, so I am anxiously awaiting word of a Lego TMNT game
I might be misunderstanding somewhere, but Lego makes Marvel sets. I've seen tons of Avenger ones, and they even have Deadpool in a helicopter (with Wolverine and Magneto too). A quick google search will pull them up.
I'm expecting Lego Avengers sometime soon because of all of the sets.