This might be quite an unpopular opinion but I don't think the master series should
solely be warbirds. Sure, they're cool, but some people like other sorts of airplanes and rendering them with more scale detail would be pretty cool. I honestly think a MS Cub or Super Cub would be pretty cool, and I'm currently in the process of building a prototype for one though it looks like this at the moment (and will probably continue to look like this for quite a long time because my abilities with foamboard leave quite a lot to be desired):
I would also really love to see a MS Waco. Maybe this is because I just love Wacos and would probably be the only person to buy it.
Other than that, I would really like to see a Do 335, but it would have to be set up with retracts if you want to keep the cruciform tail. Honestly retracts are something all the applicable MS planes should be set up to take from the get go. Belly landing scale planes is no fun!