The C committee has just deprecated trigraphs. It might be the right time to propose ≠ as alternative to != and then in 40 years we can deprecate != and only keep ≠
On Linux I use the sequence Insert, "/", "=", having mapped Insert to act as a Compose key (what other use do you have for it anyway?).
On Windows I use the same sequence, having installed wincompose by Sam Hocevar.