They wouldn't make as much as you think. Especially considering how many companies would be involved.
Take this picture for example. 7 characters from 7 different companies. Even if it sold as well as GTAV in its first days, that's $1 billion split up to 7 different large companies(companies with hundreds of workers and bills that need to get paid). Roughly $140 million. Sure that's a lot, but the likelihood of any game matching GTAV's sales at any point in the next decade is fairly low. On top of that, in my more recent pictures, I've got characters from up to 20 different universes and by extension 20 different companies. There's no way anyone involved will make any sort of profit from this sort of thing. That's why large scale crossovers between companies can never work.