I don't know how this would actually be possible, but if both accompanied were to split the cost of production and revenue would you want to see a Marvel/DC crossover movie. I think in some ways a crossover movie would blend the best of both movies. Marvel is much more light hearted and humorous, where DC tends to be dark and gritty and if they could meet in the middle I think they'd make a good movie. On the flip side Marvel has its niche and it works if you look at the money and DC despite its criticism also does very well. Logically speaking I'm not sure people would want to see the blends of each in the movies. I recognize that it would ever happen as the profit would not be there, but given the chance would you want to see it?