I was moreso thinking villains that could tie the whole universe together..
I'd imagine they'd like to continue that formula every couple phases
I dunno, seems like the point of Endgame was to put a bow on the culmination of the MCU up to that point so they didn't have to have long such long story arcs and phases. You got this arbitrary split between street level/earthly and cosmic stuff that that allows for more to be done in less time than it took to get us where we are now.
I just saw a video about how Phase 4 is going to have about as much hour for hour video time/content as the first two phases combined while only really lasting for about 2-3 years, I never thought it about it like that.
Villians like Doom and Norman Osborn if they get the rights from Sony can cross over and affect shyt way outside the range of their main stories without having to do Avenger level team ups.