Mozilla has just published a Google Doc that outlines their plans for Fennec (Firefox for Android). It looks like this document was supposed to coordinate Mozilla employees and volunteers, so the specifics are probably more “development goal” than “public announcement.”
The premise is that maintaining Firefox for Android, its Beta, its Nightly, and its replacement, Fenix, is a lot of work that could go into preparing Fenix. As such, the next Firefox extended support release, ESR68, might be the last one for Fennec. It also might not be the last version for Fennec. If I’m understanding the timeline correctly, it looks like they are giving themselves until early August to back out of this plan, based on product requirements for both Fenix and Fennec.
Either way, Mozilla is preparing a new browser to take over its duties. Fenix will be developed using GeckoView, which continues Mozilla’s mission to provide an alterative Web rendering engine that pushes standards forward. For end users, this news should just mean a little gap where Firefox for Android receives bug fixes (but no new features) until a big relaunch.