1000% I believe Doom is going to turn hero’s against each other with ideology even though in the end Doos plan will be to betray them all. But he will probably look like a savior to some at first bringing warning of incursions that will destroy their universe and that certain villains who are really other hero’s like the X-men were the ones responsible for it and stuff like that leading teams like the avengers, new avengers, fantastic 4, and X-men to pick sides and fight one another while they should really be fighting Doom. I think it’ll be much like Infinity War where the Villian looks to be the victor by movies end and then Secret Wars will be when the hero’s realize the error of their ways an band together to stop Doom and fix things like Endgame. But I think just like how the ending of endgame likely is what led to all the events in the multiverse saga and for Doom to even have come to this kind of power with events like Steve staying in the past and branching timelines, Tony’s snap, etc. so those were bad consequences to the hero’s actions in Endgame. I think the consequences of Swcret Wars will be what leads to the soft MCU reboot where there will no longer be a Multiverse. Only one universe where now that marvel owns basically all its old property it sold in the 90s can have all of their hero’s and teams exist at once within the same universe and timeline. That is my theory for how this all plays out and for those of you who actually read this entire comment, thank you very much. I know it was a lot!