I wouldn't say that. I'm sure they WILL cross over again. People at both publishers said it would never happen again after the JLA/Avengers deal fell through in the 1980s. Neeeeeever happen. And then less than a decade later, management changed at both companies, new people came in, and we got a ton of new Marvel/DC crossover stuff. Much more than ever before. So even if someone at either publisher now says it won't happen, it eventually will. It's free money for them. But as for what I'd like to see cross over: nothing. Not a single thing.