A couple ideas here. I know some have been thrown around but based on my experiences with other games my perspectives have changed.
FTP: I think this is critical if you are going to get younger players. In the games that I play that have younger players it's because they don't have a credit card and they play any games that are free or have free versions of them. Most parents are not gong to pay a $15 a month sub for their kids. These kids are usually teenagers and usually have friends that they would bring along. From what I recall HT was concerned that everybody would cancel their sub and go to a FTP account. I don't think this is true because of games like WWII online who have multiple levels of subscription and if I recall correctly the highest level is "builder" and it's close to $50 a month people pay. I really think after playing other games (some which of massive numbers of players) that his is a big barrier to adding numbers, especially youth in the day and age)
Addition of AI: One of the games I play a lot has an option for battles that last less then an hour. The battle starts with something like 20 players on each side and 20 AI on each side. The AI are all ground attack or bomber aircraft at low alt. The attack ground targets and can have a major effect on the war if they are not dealt with. The good thing about the AI implementation is that it gives new or less skilled players the ability to get kills and learn gunnery skills etc. (it keeps them engaged)
Early/Mid war. I think bringing these arenas back and offering a ftp version of high ENY planes would be a positive for those who enjoy the smaller maps and with some AI from the match play arena it would give new FTP players a place to start fighting with each other without getting thrown in the deep end at the very beginning.
Two countries: Most all the other sims that I currently have a 2 country war and are somehow still successful. I'm not sure why people are convinced that it is not possible for a 2 country situation to work. I'm not sure that it would fix the balance problem but it would be interesting to see how it changed the dynamics and could always be rolled back.
I know some of this stuff has been discussed already but I'm trying to explain my reasoning behind it because I see the effort that people like Animl-AW are putting into this stuff and I think that maybe somebody who has HTs ear may be able to help by considering some changes on a trial basis that would add numbers.
I don't think any of this stuff would take much dev time. The match play AI already exists and the other stuff shouldn't be difficult to set up using custom arena settings.
A FTP HTC hosted early war arena would be fun. Especially on a small map. It would give players a chance to learn and understand the game. Give players on the fence a chance to see the game, and it would probably entice them to want to try the MA. I certainly agree that what the game is missing the most is a feeder arena that people and noobs can fly in with no score and quick action so they can get into the action. Flying for 10 minutes and then seeing action, and then dying fast, seems like a time loss and most people just don't have the patience.
A FTP early war arena could be set up in a custom game too. Just need to spend time setting it up, and sitting in the arena waiting for players to show up. That's the tough part. This is why small maps matter. With 5 players on, you want to know where they are and be able to get into the action and skrimish over a few bases in the same area. Big maps overwhelm the eyes. It's why Smog8 was such a great map during team death match H2H.
AI would be fine in it's own arena, but not in the MA, only because it will have major implications on scoring and of course how do you yell at a AI about it picking you! And what level of skill do you put them at, ect? Just too tough to put in the MA. They are really good in the match play already and it's actually great for practice, however I feel the hurricanes are just too tough. Should be replaced with like a P40 or something. Hurricanes with super E are too tough for most noobs.
2 sides just isn't going to work. No other game really has the global atmosphere that AH has. Server matches are a bit different. Heck, even the real war had more than 2 teams. 2 teams will just become lopsided too. Plus you'd have to redo all of the maps. But I would prefer to have custom arenas like TDM like H2H use to have where there was 2 teams and it was smaller and more compact type of battles.