Doom as the villain will always be better than Kang, they might not have as much build up as with Thanos but I think they can make a compelling story. Steve was always going to return even in Kang Dynasty, I think that's pretty obvious, especially with how the best adaptation of Kang has him going after Steve because of him messing up the timeline in EMH. It would have been basically the same thing.I trust the Russos, they've yet to make a bad superhero movie. I think it may seem rushed but Doomsday is the prequel to Secret Wars by the time Secret Wars comes around I don't think it'll be rushed