What NX is is pure speculation and rumor,so no one has any idea what it really is. Whether it's directly replacing 3DS or not doe snot really matter,by next year 3DS will be 6 years old so it's on it's way out either way.
The thing is, this is still kinda funky territory. Can't really come to a decision without seeing how it affects people. Look at the internet and everything that it's done...nobody could have predicted every little detail about it because it has so much potential. Same with NX, not sure what to make of it.