Hmm, does this mean that large swaths of people publishing apps are going to flock to distribution platforms like f-droid?

(Yikes)

F-Droid only accepts open source apps.

absolutely, i get this. i assume it's going to be a relatively small subset that go open in order to jump to an open platform. i'm not super familiar with the f-droid publishing ecosystem (or mobile publishing at all, admittedly).

i do wonder if there's regardless going to be some kind of (perhaps overwhelming) inundation.

This is probably why they killed installs that dont have attribution, specifically to undercut f-droid.