Sounds like it could be loads of fun.
Why AA2? Is it just your personal preference or that of someone else's? I know AA2 was incredibly popular (for it's type of game) around 10 years ago, but it was free. A paid game will likely be at least somewhat different.
One of the things that made AA2 good (IMHO) was the fact that it was relatively slow paced (compared to CS or CoD for example) and that required some tactics and teamwork to be used in order to win. I would hope the same would be true for this game.
With the way it looks right now, the UI looks like a blatant rip off of the US army's product. Are you confident they won't feel the same way?
A lot of the things in AA2 that make it great for those who enjoy it are to do with the game mechanics. However, not everything in AA2 is pure gold. For example, IMHO the ability to hear people from across a map is really unrealistic IMHO. The same goes for hearing every little "click" a gun makes (i.e when stopping or starting running). The clicks can be there (and if you put safety on while running, it would be), but it should be way quieter. I really like that walking/running on different materials in AA makes different sounds, but the idea of "slow crawling" without making a sound is just silly. You try laying down on the ground and moving without making a sound - it's impossible. Your clothes will rub themselves and the rest of your gear.
And of course it needs to be a modern game with modern graphics and therefore modern system requirements. As much as we would like to think that people like what's in a game (i.e game mechanics, maps and so on) more than the looks of the game, I'm afraid that's simply not the case in reality.
However, I would like to point out that the people here are a
vast minority of the people your new game would have to reach. These are the people who've stuck with a game after it's been officially shut down for 6 years. They don't like change. They like AA2 the way it has always been. All this is great, but selling only to those few people won't be enough for a new game.
With all that said, I wish you good luck with the game.
EDIT:
I can't just copy maps for commercial products. But I can get some heavy inspiration from the original ones. As I said if hospital would now be in eastern europe and some rooms would be in other order - it would not break anything.
Wow, Eastern Europe? I live there!