Taking ideas from fans is never a good thing; ORAS happened because of fan demand, and look how that turned out. Not only does it limit a company's creativity, but there's also the issue of lawsuit if a companies in general, not just Game Freak, ever try to use a fan's idea. You just have to pray that one of their ideas they came up with in-house coincides with a fan's idea to avoid any possible lawsuit. The image I showed you about how the three systems parallel with tablets, smartphones, and PC should tell you that NX may not be a fusion but possibly a PC system, which obviously the mainline Pokémon games won't be moving to (only the 3DS's successor).