lets return back to reality please
let me make this very clear - a 2048 x 1536screen resolution tablet Will. Not. Happen. Ever. there is absolutely no reason for it and about 1000 against it. To name a few:
1. There is no media content that can make use of it, so processing power would have to be used to upscale everything.
2. Nobody, bar the extremely anally-retentive, complains that the resolution of a 24" monitor running 1920x1080 is too blocky or poor resolution, so how would a screen at less than a 1/4 the size be improved by increasing the resolution beyond 1080? 99/9% of people wouldn't be able to tell the difference, so why waste money on it?
3. Such a display would be way beyond the cutting edge of display technology and Apple have never even strayed into the cutting edge with their products, let alone beyond it. Apple take well designed mainstream tech and package & market it well. why should they suddenly change their whole method of working?
4. Running any kind of 3D games (portable gaming is an area where Apple are clearly moving in to) at that resolution would require a +400W power sucking fullsize desktop GPU
5. There are much better & cheaper technologies on the market that can improve the image quality of a screen than just ramping up the resolution, so why waste resources on that approach?
Now I could see a 10-12" screen maybe going as high as 1920x1080 in the future, but not for the next couple of gens.