Sadly emulation is seemingly non-existent for newer consoles like PS4 and Xbox one (PS3 is pretty emulatable but fairly demanding, Xbox 360 emulation is last I checked still pretty poor) Luckily most of the games on newer consoles are released on PC.
I remember ps3 emulation a few years ago was determined too hardware intensive, nowadays it can be done on mid level hardware. PS4 and Xbox One is going to happen, just depends on when.
Yep. The PS4 and Xbone are both very close to off-the-shelf AMD APU's as far as I remember; you could buy very similar processors for desktop use. Emulation would require a ton more power than the original chips, and the original chips are so close to desktop processors that it's more efficient and feasible to reverse-engineer the proprietary API's those console chips use.