The Aerostar won't be first...

My guess would be the Cub. Its one of the most recent upgraded planes with the new textures which I believe is all PBR. However, since the MSFS code is really not set for more advanced addon planes right now, going with the basics of stick and rudder and a simple panel layout would mean they wont have to spend a lot of time bringing it more and more up to code as MSFS develops.

Ideally, I look forward to all their planes making their way into MSFS as well as what this new Accusim version will offer. However, I still feel a simple Cub would seem the most likely to go ahead and put out there.