I saw on some website that there may have been some plans for a sequel had Capcom not lost the rights to Tatsunoko characters. Apparently Evil Tekkaman was considered, but this info may have been faked.
I genuinely think that in some ways Tatsunoko VS Capcom is better than Marvel VS Capcom 3. The graphics are quirkier and give an arcade like feel no other game can ever hope to match, and the controls are fast, but not so fast that you can barely see what's going on, like in MVC3. But then again, MVC3 surpasses Tatsunoko VS Capcom with more characters, more responsive controls, more fanservice and has more 'crossover value'.