Edge provides a compelling alternative that is a drop-in replacement for Chrome for most users. I wonder if the competition will keep Google in check. I also wonder if Edge will end up providing its own ad-blocker if Google's restrictions become too onerous. Probably easier than forking the core browser to maintain a parallel build without the extension limitations.
AFAIK all chromium based browsers will follow Manifest V3. Edge will also as otherwise adblockers and the like would impact M$ revenue.
Manifest v3 is just everyone's get out of jail free card for not being responsible for the destruction of ad blocking and privacy extensions. Blame it on Google, who says they "had to do it" for some reason that ultimately profits them and their ilk to the detriment of humanity.