Another day, another slew of contradictory NX rumors. However, I will make a few comments:
1. It seems that if the NX does end up using x86 architecture, then I can see the rumors of shared architecture between console and handheld not being true. Never believed those rumors anyway, but I can still see some cross-buy implementation similar to the PS4 and Vita.
2. In terms of backwards compatibility, I think Nintendo cares too much about preserving their games that I can see it happen for the NX. However, it doesn't mean that the hardware is going to be PPC based. Seeing how far the Cemu emulator has come, I can see emulation being a possibility, and I can see it running better than 360 games on Xbox One if the NX ends up being more powerful. Also, another thing to point out is with Nintendo's SCD initiative, if they do implement it on the NX, they could possibly release an extension to the NX that can allow for backwards compatibility if they don't want to charge the user up front for it.
Anyway, those are just some thoughts.