uBlock Origin developer recommends switching to Firefox as Chrome flags the extension
About Google Chrome's "This extension may soon no longer be supported"
https://github.com/uBlockOrigin/uBlock-issues/wiki/About-Google-Chrome's-%22This-extension-may-soon-no-longer-be-supported%22
This is the community-maintained issue tracker for uBlock Origin - uBlockOrigin/uBlock-issues
EDIT: Apologies. Updated with a link to what gorhill REALLY said:
Manifest v2 uBO will not be automatically replaced by Manifest v3 uBOL[ight]. uBOL is too different from uBO for it to silently replace uBO -- you will have to explicitly make a choice as to which extension should replace uBO according to your own prerogatives.
Ultimately whether uBOL is an acceptable alternative to uBO is up to you, it's not a choice that will be made for you.
Will development of uBO continue? Yes, there are other browsers which are not deprecating Manifest v2, e.g. Firefox.