Shredder? That's interesting and at the same time it'd be somewhat fitting. Bethesda shouldn't have even thought about it for a second. they should've just went to Netherrealm and be like: Hey, our new game is coming out and we would like our character to be in your game, we feel that Doomguy would be a hype character in MK11 and this would also benefit us, or more specifically our new game in terms of promotion!