After season 4 of Rebels has aired, we could expect to see a Partisan set featuring the Partisan X-Wing and U-Wing with what I can imagine improvements over the previous U-Wing expansion. Pilots we may expect to have are Saw Gerrera, Beezer Fortuna and Edrio "Two Tubes".
Also the new TIE Defender flown by Sabine might mean we'll get it for Rebels.