the next adon will most propably the memntioned "Battle of Moskau" - that means a timeframe late 1941 to early 42, eastern front:
possible planes (no coplete list for sure !

)
Bf109F-2 (perhaps -4)
Bf109E-7/B
Bf110E
Hs123
Hs126
Ju87B/D
He111H
Ju88A-5, -4
I-16
I-153
MiG-3
Yak-1
LaGG-3
P-40B/C
R-5
IL-2 (single seaters)
Pe-2 , -3
DB-3
SB-2
i doubt there will be intermediate AdOns for the new IL2 series to sell planes for another scenario on a given map (like Dieppe 42)!
Hopefully there will be some free adon planes in needed patches....but i guess far of the amount as in the old IL" series . These times are over.
IMHO, 1C should give the RAF one more flyable bomber , as the Wellington is there already as AI, use the Wellington (even if my persoanl favorite would be a Hampden !). Make a Bf109E-4 and E-1 ( should be not so difficult) ad a Hurricane Mk.II , sure fix all the stuff in game (

) and than soldier on to the next Full AdOn , the mentioned eastern front scenario !