OBD likes to surprise us with new things so I can only speculate on possible types that might show up in the future...perhaps the:
(a) Morane Bullet
(c) Pfalz Dr.1
(d) Siemens-Schuckert D.1 (Nieup. 16/17 imitation)
(e) an early pusher/bomber...such as the AGO C.1
The above thoughts are strictly my own.
(Although we have a lovely selection of aircraft already in WOFF.)