A lot of people in this thread are missing the point of the OP's idea. I don't think he's really talking about War Thunder itself, but more of the idea of meshing Hearts of Iron-type grand strategy with War Thunder style (ignore the pay to win crap) tactical combat. The general idea is that you would play HOI as normal, but when you wanted to you could zoom in on an ongoing battle and take individual control of units on a real-time battlefield, from divisional level maybe even down to individual soldiers, pilots, tanks, etc. So basically you would be meshing an FPS, RTS, and grand strategy all on a seamless, real time map.
Of course the computing power necessary for this would be ridiculous and I can't see anything like this happening for something like 10 years at the least, but I do think someone will eventually try it out because it would be the ultimate World War 2 (or whatever war you're playing) simulator at all levels.