This is not guaranteed.
Firstly, “non-binary” is often a step towards identifying as the opposite sex, particularly as puberty approaches and particularly with parents who enable the idea that puberty is somehow optional. This leads to the fear of upcoming male puberty determining for sure that the child will physically move towards one of the two sex binaries, and push the child towards wanting action to prevent that happening.
Second, gender clinicians have argued, in medical journal articles, that it is ethical to use puberty blockers to keep a child’s body in a “non binary” state forever (which in reality, is forever pre-pubertal). So it’s not beyond the realms of possibility that a practitioner somewhere would facilitate this.
I think the second option is less likely. The first option happens all the time. Gender clinicians say the non-binary status was “just part of the journey”.