It's hard to believe MHW, RE2 and DMC5 were published by the same company as MvCI. I really want them to make a fighting game with the same amount of love and polish. I agree with the OP that the unique funky aesthetic of MvC2 is part of why it's so well-remembered, but I think in broader terms a new game just needs to be eye-catching and have some kind of identity. I think MvC3 nailed this and is one of Capcom's finest audio-visual works to date.
Brand recognition means MvC4 or SF6 would probably do better than a Capcom All-Stars or Darkstalkers 4, but if they were to make a game that's visually striking, had an acceptable amount of content at launch (preferably not consisting of 80% reused assets from the last game like MvCI) with a steady and transparent plan for ongoing support, and combined classic gameplay with new mechanics that are fun to experiment with and rewarding to use, any of these games could get people talking. NRS and Smash games get this insane word-of-mouth hype buzzing as soon as they're announced, maintain it with community engagement and frequent development updates until launch, and upon release they're met with glowing reviews and record-breaking sales. Capcom insists on ignoring this formula and instead continuing to rush their fighting games out and bank on DLC profits coming in later. They're good at making their fighting games fun, but that matters less and less when they're so willing to throw away the community's good will at a moment's notice.
Don't release a $60 game that feels like it was made to sell us DLC, don't allocate an exorbitant amount of the budget to a throwaway story mode, just try to give us a game that's going to earn some good press up until release and have legs to stand on moving forward. I like SFV but I think it's fair to say MvC3 was Capcom's last real fighting game success story, and with 8 years having passed since then, it's becoming harder and harder to maintain any faith in Capcom's fighting game division.
