But this would insert lag into the gaming experience? Gaming by nature has to be realtime.
Yes. It's well know that Fake Frame generation adds lag. Generally 1 full frame time, of the real frame rate. So if you are running 60 FPS real, then you add about 17 ms of lag when you turn on fake frames.
Not much should change in lag by adding more fake frames.
I'm under the assumption that using your analogy it only needs to predict what the screen will look like for 3 frames. So instead of computing those 3 frames, they are predicted. Assuming you are running 100fps, that's 3ms or 1 frame per ms. The 4th frame is then computed. Since only 3 ms has transpired unless there was a complete scene change the difference between the 3rd predicted frame what that actual computed 3rd frame would have looked like will be basically nothing, so then the moving from frame 3 (predicted) to frame 4 (computed) would be smooth.
I don't like predicted, because it's not a future looking operation. They are interpolations between two known frames. You are always figuring out positions in between two frame you already have.
I would assume that the faster the hardware can natively run the game the more predicted frame can be used. So if the game is running natively at 60fps maybe only 1 frame can be predicted between computed frames. But if it's running 150fps, then perhaps 2 or 3 frames can be predicted.
I would think it the other way around. The higher your native frame rate, the smaller the window between frames, to insert your fake ones.
60 FPS = 17ms window to insert fake frames.
240 FPS = 4ms windows to insert fake frames.