All valid questions, but it might be that splitting the tool used to bludgeon everyone around is still worth it, even if pace of development slows down considerably.
Unless you are using Chromebooks, every desktop user who uses Chrome made an affirmative choice to download it.
My point is that maybe it is okay? Runaway churn is at least partially responsible for current situation, where most companies simply unable to compete.
Apple has no reason to compete, it can just make more and more functionality for native apps as can Google if it doesn’t have to worry about Chrome anymore.
Microsoft doesn’t care about the browser anymore and just uses Chromium. Firefox’s revenue comes completely from Google. If Google doesn’t have to prop up Firefox for antitrust reasons anymore, why would they?