I'm not an expert here, but I this is pretty unlikely at this point.

Google has been working on Fuschia for a decade, and far as I can tell, the only place it was ever deployed was to a Google smart home hub 5 years ago. The only Fuschia news I've heard since then was about layoffs and killing projects related to it (e.g. Chrome on Fuschia).

If Google isn't moving any of their own phones over to Fuschia after a decade of work, it's hard to imagine them unilaterally flipping Android to it and forcing the hand of every Android OEM to follow suit.