We are NEVER getting MvC3. The MvC series came out when Marvel was a dying company; characters were cheap and Capcom was able to purchase them with relative ease. Now, Marvel is far from a dying company; Marvel's movie studio has brought the company new life. Now, the price of characters isn't as cheap.
Instead of Capcom being able to purchase the entire Marvel catalogue for a low price, now Marvel charges a large fee for each character INDIVIDUALLY. This is one of the reasons why you see those other games like Rise of the Imperfects with such a limited cast of Marvel characters. Frankly, the fees are so large that Capcom doesnt want to pay for it...
Thats where Tatsunoko comes in... Tatsunoko is now a dying company; and unlike Marvel, their movie studio has been continually failing to bring the company around. Speed Racer was one of the most expensive movies ever, and it was a total flop. Before that, the Robot Hunter Casshan movie also failed. Basically, Tatsunoko is now, what Marvel was 10 years ago.