I would be interested in playing a waw mod if come close to this direction:
1) Do upkeep: It is not preference or idea, it is a must especially for bigger maps. Millions of units are not needed, they bring nothing other than more calcultion troubles. And growing stacks mean greater risks like might losing a game due to miscaulcation.
2) Draw option: Comebacks, surprizes and uncertainity until the end are fun but rarely present in TripleA games. They usually ends in a nowhere very anti-climaticly. In reality Germany reached its military production peak in 1944 certainly they have still hope in that point.
3) Avoid "must be done" stuffs as much as possible: Instead make all of them real choices with pros and cons for more replayability. For example why is Russia railroaded to spam always 6HP per round in Sibirsky in here? Why there is no downside in this purchasing which should have been. It is something every allies player must have to do but I ask why? Why there is no more option other than spamming 6 hp per turn in this area?
4) Starting date: There is no surprize France will fall and its not interesting. The most appealng parts of the game obviosuly Barbaross and Japanese expansion which plenty of options. I do believe 1940/jun or 1941/Jun are the best dates for WWII scenarios.
5) Two-Ocean Going USAThe US in waw is not really two-ocean going one instead predictable one similar to Sibirsk factory issue. Its expected to follow always very similar routes which lies on spamming HP (whatever it is) to contain Japan first and sending token force to N.Africa/Spain. First USA should not have been deprived "Germany First" option and "Japan First" should have been just a strategy among others not a railroaded task.
6) Get rid of minor nations: 5-8 nations are enough the others presence not outweight their minus of slowing down games.
7) Set-Up: There are just too much unit, better to have fewest units as much as possible to speed up.