Once the CT is out of the way and resources can again be committed to adding new aircraft instead of updating and improving the old ones (not that they aren't doing a great job), I think maybe it might be an interesting idea to work on releasing 2 or 3 planes at a time, each set linked by a common theater of use and period in the war. All things being ideal, have like to have at least 1 fighter and bomber for each the Axis and Allied sides by year and part of the world, for example (and just working from the top of my head here...)
1939-40
ETO
Allied- D.520, MS.460 and Hawk 75 for the French and PZL P.11 or P.24 for the Polish fighters; the Vickers Wellington and one or two of the Bloch or Potez bombers and the PZL attackers.
Axis- Bf109D, Fiat C.R.42 and Fiat G.50 for fighters, He111 and SM.79 for bombers
Pacific/Asia
Allied- Kind of hard since the war with the major allied powers didn't really start until the end of 1941 (aside from the Chinese) but maybe the Buffalo and the Blenheim to fill it out a bit?
Axis- A5M2 Claude fighter and G3M Nell bomber
1941
ETO
Allied- This could be the big one, as you have the Russian aircraft from Barbarossa- I-16, Yak-1, LaGG-3, and MiG-3 for fighters, plus the Beaufighter; Pe-2 and Il-4 (plus an earlier version of the Il-2 maybe), plus the Beaufort
Axis- IAR-81a and Re.2001 for fighters, Do17 and SM.84 for bombers
Pacific/Asia
Allied- P-39 for fighter, TBD Devastator for bomber
Axis- Ki-43 Oscar fighter and G4M Betty bomber
1942
ETO
Allied- Fighters are pretty well fleshed out for the allies, but they could have the Martin Baltimore and B-25C, B-24D for bombers. Would work for ETO and Pacific. [EDIT] I forgot, maybe the La5 and La5F to go with our 1943 La5FN?
Axis- again not much room for fighters, but could add the Piaggoi P.108 and He177 for heavy bombers, Hs. 129 for an attacker
Pacific/Asia
Allied- see above
Axis- Ki45 Nick
1943
ETO
Allied- fighters are pretty full here too (unless you consider the P-63 for the Russians), but the B-17F could be added
Axis- Reggiane Re.2005 and Fiat G.55 fighters, IAR 81c
Pacific/Asia
Allied- SB2C Helldiver and B-25G (version w/ 75mm cannon and 4x MGs in the nose)
Axis- J2M and Ki-44 fighters, B6N2 and D4Y2 bombers
1944
ETO
Allied- dont think theres really anything to be added here
Axis- ditto
Pacific/Asia
Allied- if you say "B-29", I will kill you, but maybe the B-25H (with 8 nose mounted MGs plus the cheeck packs) and the B-25J for level bombing
Axis- maybe another armament version of the Ki-84, or add the Ohka bomb as a perked Me163 type ride
1945
Nothing to really add here for anyone unless you want to get into adding things like the Do.335 or Kyushu J7W1 as perk rides.
Although some sets might need to be broken up (early war) and some are pretty well set as is (late war), it might be easier for HTC to do it in matched sets like that than to just randomly pick and choose from the vast library of WWII aircraft. Most of these were common enough to be considered but also unique enough not to be redundant (noticed I skipped over the multitude of Italian 3 engined medium bombers and settled on one or two), and all would add something to the current setup, even if it is just to balance out a specific period or theaters planeset so we dont have to keep using subs in scenarios and AvA matchups.