I hope not. Only AMD can offer a big CPU upgrade and a mid-range GPU in the same chipset for a good price for next gen imo. Going with a separate CPU and GPU would complicate cooling, be expensive, and ruin backwards compatibility if they went with Nvidia + Intel instead of AMD + AMD.
Yes maybe so, but if the rumours are true about MS going full Cloud streaming for there base model which will offer as much power as there top tier console, Xbox can release there premium console with what ever they want in it which we all expect it to be expensive.
As for Nintendo, they already went Nvidia and Sony well, AMD works for them but I much rather prefer Nvidia over AMD and I am one customer happy to pay the difference.