I'm afraid if schools are not going to have legal restrictions here (Keegan gambit), and the AG advice that restricting pupils changing gender transgresses the EA, then I can see one of two scenarios.
Parents see no guidance from central govt, either moral or legal, and will feel they'll get no help from schools (teachers, the head) and local education authorities, more and more will feel helpless in objecting to their kids transitioning. And the phenomenon gets entrenched, more and more normalised, and parents/teachers objecting more and more sidelined and silenced. And the phenomenon grows in prevalence and depth.
This, but Generation Alpha take it into their hands to stymie the trend. As said before, young teens and proto teens will see what was a wacky and colourful counter culture movement become promoted and protected at school, and rebel against the new conformity.
The latter will involve an increase in verbals and bullying, a whole group of victimised special kids, a whole bunch of suspended and expelled pupils expressing GC views, and their parents rung out as well.
All because adults in charge failed to make the right decisions when the phenomenon became visible, and then allowed so much momentum and froth, that dealing with it at a later date (ie now) is even more challenging.
Maybe it really will be the kids that will sort it out, certainly the adults seem unable (or unwilling?) to.