In the recent layoffs I've seen some very senior high-performing engineers get the axe, because they were very expensive and the org could get two juniors grinding out CRUD for the same value as one super senior architecture astronaut.
Ditching an architecture also directly implies adopting a new one. If juniors are at the forefront of that, I don’t think the resulting architecture will somehow get magically simpler.
Architecture is a topic to be debated, no doubt. But if anything, I’d expect the departure of senior talent to solidify complexity, not enable some magical escape from it. The risk of changing a system goes up significantly the moment the people who understand the system walk out the door.