I think a genre that could have been even bigger than it was, and has always died off because of greed is those figure collecting games such as Skylanders or Disney Infinity.
It's very clear that the main downfall for games that try to do this is the price they sell the characters for, not only that but they added vehicles and locations just to suck up even more money out of their fans, and the kids who see them in shop windows.
Im a dream world it would be ground breaking if Sony and Microsoft would join together and make a mega version of this genre that has characters from both consoles. I honestly think this would work because the majority of gaming fans collect figures for their favourite characters anyway, so if they could get a figure AND have it fight alongside characters from other consoles it would be amazing. Imagine Master Chief working with Kratos against villains from both games.
To have this work however, they would need to sell the characters for an affordable price, and if they REALLY need more money, then just make a separate rare looking version of each character for more money, so the normal versions are accessible to anyone still.