All they have to do with that diablo game is rig it to be usable by PC gamers. There are already conversion programs you can download for other mobile games. So they just need to adapt this tec and allow their customers play the new game on both platforms.
As for WoW. Well all the useful posts on how to fix things is buried inside GD under a mountain of crap. But if they dig they will find the solutions they need to fix this game. However MOST of it involves putting aside their own massive ego and stubberness. Also the fact that they move at snails pace is not helping. They could have gotten worgen and goblins done 2 years ago.