Marvel. Batman has a lot of pull in the US, but injustice is not Mortal Kombat and won't do it's numbers. I see this being the best selling Marvel yet. It will definitely have longer legs with dlc and all.. and I think it will be a better game even if you don't get everything you wanted from the previous games.
Now that being said.. warner bros. may slaughter Disney/ Capcom in the Marketing arena. MvC3 was made a lil bit after the Marvel acquisition, so with their new focus on the games division, we'll see how many dollars they put behind it.
That's seems to be the real battle, how they handle dlc, reviews, marketing and the community (just straight up awareness).