Nintendo had hinted that it will not just be a stonger WiiU.. So to answer the qustion we need more info.. (How is it different)
is it upgradeable/modular.. Is there some kind of pc/steam possiblitys.. How will it interact with mobil/tablet.. Does it use some new kind of VR.. are there more forms.. will it be cheap or expensive.. And much more..

Point is.. We dont yet know why we should buy it.. what it is it can.. do.. whats the magic..

(AND.. If NX goes on and sell more than ps4.. I think all people would still say that ps4 won this gen.. NX is next gen.. and therefor ahead until ps5/two comes)