Asking what game system will run on is pointless.
After the Alpha stage they begin beta testing which takes many months. During the beta testing many incarnations are made, ideas improved, discarded etc.
Once all the above has been done and they are happy with the basic project they start optimising the game to run on the lowest machine it can.
This also takes into account current drivers from the big two GPU card manufacturers.
This optimisation goes on even after the product has gone gold and really never ends.
Features will be added as the various phazes of SOW are introduced.
Each new feature will require more bang for your buck.
The orginal Il2 ran on perfect settings on my ATI 9550 many moons ago.
Now I have a 8800gt and the current incarnation IL2 1946 runs fine on perfect settings except i am now running it on 1440 x 900 resolution where as on my ATI the settings were 1024 x 768. If I tried to run Il2 1946 on my old ATI system I doubt I could even get medium settings.
So moral of the story, wait be patient and you will find out when it hit's the shelves.
Until then buy whatever you need to play what you want to. Oleg has proved in the past that he makes his games perform well on low end machines.
Try flying Lomac (Lock-On Flaming Cliffs) and you will realise how backward some flight-sim code is.
On my not-so uber system i am at stages reduced to flying on medium settings and that sim is over three or four years old
