The same guy who leaked the original information about Super Street Fighter 4 has said that Marvel vs. Capcom 3 will be announced in May.
If it's true, then they just started development. So maybe this time next year the game will be out. So no, it won't be longer than GT5. Here's the thread on the Marvel vs. Capcom 3 rumor. http://www.neogaf.com/forum/showthread.php?t=392234
Picked up Super yesterday. I only played it for a little while and so far it's a huge upgrade to SF4. Only $40 too.
Super Street Fighter 4 Arcade Edition is on sale, $20 brand new at Gamestop. Both the PS3 and 360 version.