They're working on a replacement for 100LL avgas, thankfully.

There's some flight safety concerns that have delayed it, but it's still a work in progress.

Last I heard the project has stalled. And with the current administration there's unlikely to be political pressure to get it rolling.

The concerns I have around the project are more in the FAA certification process than in the EPA. I don’t believe this is a partisan issue; it’s stalled under both Democrat and Republican administrations.

I think that the 737-Max issue will put so much more spotlight and brakes on anything that seems remotely risky, that the alternative fuels program (which was already struggling as you note) is unlikely to make serious near-term progress.

Almost tangentially, I believe that we have a viable fuel technically (G100UL) that is likely to be (or be the template for) the fuel ultimately selected, albeit possibly a decade or more in the future.

Last news I've seen is https://www.avweb.com/air-shows-events/unleaded-avgas-all-on...

There's also some news at https://www.faa.gov/about/initiatives/avgas/ , but nothing substantial..