Capcom have discussed why bringing over Tatsunoko vs. Capcom is still a problem, and that we might never see a Western release.
Capcom's Seth Killian spoke to Joystiq last weekend on all things Marvel and Tasunoko, noting that a majority, if not all of the issues surrounding releases for these fighting games are down to licensing and lawyers in the US, and Europe too it seems.
It's a lot of 'dance with the lawyers' on that one. The rights holders for Tatsunoko in Japan are one company, but in the U.S. it's ... 13 companies -- and some are very attentive and some are not.
With that in mind it's looking even more unlikely that the game will receive a Western release, but it won't hurt to hope, just a little.