The only thing that changes equilibrium constant is temperature -- and since Kw is such a constant it will change with T.
It then follows that the pH of water will also be changed by temperature -- and yet water remains neutral...
A better definition of neutral is [H+] = [OH-] (since water is only pH 7 at STP).
An acidic solution has is [H+] bigger than [OH-]
a basic one, is [H+] smaller than [OH-].
