AH2 will replace AH1 but the MA will be the same as before only much better. What they did was update the flight dynamics, fuel burn for the different planes, newer better looking graphics, new effects, new field layouts and the list goes on. It's just plain better

AH2 TOD will be coming along later which is more of a recreation of WW2. Where you try to suceed by achieving the objectives of each mission as a single pilot would in WW2 with the help of your allied fellow and superior officers. This will be in a separate arena as the Combat Theatre, Special Events Arena , Dueling Arena, Training Arena, etc. are.
If you've tried AH2 beta and you're worried that your PC won't cut it.
Yes. Our benchmark system for AH2 is roughly a PIII 900 with a GeForce 2. That is the design limit we are using for nice playability. The minimum system will fall under that, but we won’t be able to give specifics until we get further down the development and testing road. The new graphics engine in AH2 will be much more video card dependent, so even if you have a slower CPU, a better video card may be all you need to upgrade
Note that the minimum system will have lower requirements.