There are non-binary people who still believe genders can suit others, and even be played with as forms of role play ...and there are also examples of null states, such as nullos and asexuals...
...so non-binary doesn't necessarily make a new binary if they still believe gender is fine for others, or as a role play.
A better way to think about it might be as a gender spectrum or quadratic continuum of varied characteristics and overlapping body forms and sexual preferences/behaviour.