505
4 browsers that will continue to support uBlock Origin and other ad blockers with Manifest V2
(www.xda-developers.com)
This is a most excellent place for technology news and articles.
The answer is more than one, because Firefox has several forks of its own, and as far as I know all of them (even Pale Moon, which is highly divergent and never supported Manifest V2) support uBlock.
I agree that all Chromium-based browsers are going to drop support sooner or later.