Just did a quick look through. At present Gennadich have shown us these planes:

Allied Scouts
Nieuport 17 *!
Nieuport 28 *!
Sopwith Camel F.1 *!
Sopwith Dolphin I
Sopwith Pup *!
Sopwith 7F.1 Snipe *
SPAD VII.C1 *
SPAD XIII C.1 *!

Allied Multi-seat planes
Airco DH4 *
Airco DH9 !
Bristol F.2b *!

German Scouts
Fokker D.VII *!
Fokker DrI *!
Pfalz D.XII *


German Multi-seat planes
DFWC 5
GOTHA *
Halberstadt CL.2 *!
Rumpler C.IV *

* present in Red Baron II/3D
! present in Flying Corps

Which leaves these planes which were present in either RB or FC:

Allied Scouts
Airco DH2
Morane Bullet
Nieuport 11
Nieuport 24
SE5a
Sompith Triplane

Allied Multi-seat planes
BE2
Breguet 14
FE2b
Handley-Page
RE8
Salmson 2a2
Sopwith 1.5 Strutter

German Scouts
Albatros DII
Albatros DIII
Albatros DVa
Fokker E.III
Halberstadt DII
Pfalz DIII

German Multi-seat planes
Albatros CIII
Aviatik C.I
Hannover CLII
Roland CII

I imagine the SE5a and the Albatros DIII and DVa are almost definitely on the list to be modelled; probably the Sopwith Triplane too. Interesting to see what we do wnd up with; to the best of my knowledge the Dolphin is a first appearance in a commercial sim.