I honestly think what is going to happen is that the trans lobby will shout loudest and will get their way, until enough women are hurt and many more are unable to take part in public life because they’re to frightened to leave their houses if they can’t access women only toilets, and the general public see what’s happened and we get our spaces back.
Once done, this will be almost impossible to undo, however awful the impact upon female people. Another reason to keep urging the govt not to rush into this without very careful thought.
How could it be undone? It would then be framed as removing rights. You couldn't create a new space for females; the issue now is that saying that female humans are different from males who identify as women, and those females have specific needs for spaces of their own and times when sex is recognised as the deciding factor denies validation of identity.
That is the sticking point. That all the time you meet female people's needs you deny validation of identity to the 100% degree demanded for those male people requiring it. That drive for validation is why no female need matters or can be heard or recognised.
The issue here is fear of boundaries, and to say no. That needs will be met, but that 100% cannot be agreed where it conflicts with meeting the needs and rights of another group. Now it would still be possible to separate gender from sex, and to provide third spaces. The public anger likely to be raised in the case of the inevitable harm to female people is another very serious concern.