I love the sound of this - Male people remain using male spaces (whether changing areas or whatever) and Gender is recognised as a belief system, not a fact, so is indeed regarded as important as far as equality and discrimination go.
It does mean of course that there will be no transgender sportspeople, with a small number of exceptions where they truly are exceptional or where sex is irrelevant.
And perhaps, helpful, as with other belief systems, to provide safe spaces for people sharing a belief system to come together..... Putting some creative thought into this, it does probably mean unisex bathrooms, etc ie spaces where all can feel comfortable
And of course it does mean a massive cultural change for men regarding acceptance ......