I would like to see:
Any version of the P-51A/A-36....would look nice alongside the macci 202 and spit 5, and underrepresented in flight sims.
ANY russian meduim bomber
Late model P-39 or P-63, for the Reds
A useful German Medium/heavy bomber, to make an Axis Versus Allies area viable.
Any plane that can land in the water..PBY, H6K, H8K, etc
Lastly, If other late-war "almost-made-its" are added, then the P-51H should be added too. Actually saw service in 1945 (but not in combat), top speed of 470 or so--would keep the pony competative.
Personally though, I don't care much for the 1945-1946 "superplanes"
--Belanger