As for the BC problem it doesn't elimated BC but makes it harder. If you remeber Xbox/360 BC was spotty, some games were not able to play, this is because of the optimised coding that used nVidia's propritary code (machine code). And they had to make the emulator work around it; the more optimized the game's engine made was, the harder it was to make work arounds in the emulator.
I don't remember but that is one of the reasons why they went through the trouble of offering the game online because they changed the engine, that contained the problematic codeing, instead of continuing to try to work around the machine code.
I doubt they will have an extra chip(s) on the PS4 since they will still have to pay nVidia for the use of it and paying two different companies for GPU's is a little steep and not that great of a business model.
