That trial they'll be running isn't even live yet, and isn't even set in stone, either, and is limited to just a few countries in APAC. So, even with the news, it's still 2y away at a minimum for the US/EU.

Part of the big success of sideloading is that few people are doing it in the US/EU, so the attack surface is smaller as a result.

If few people are doing it, then unfortunately the attack surface for Google extinguishing it is smaller too.