You've summarised very well my own lines of thought over the past few days.
To some extent this might hinge on whatever guidelines are issued by the EHRC. Historically they've been next-to-useless, but with Falkner at the helm they seem to have received a belated dose of common sense. For those of us, me included, who work in captured institutions, it would be useful to keep an eye on their published policies on inclusion and to report any breaches to the EHRC. The waters are muddied by the fact that these people can, but don't have to, provide mixed gender and single sex facilities.
For eg., one such instutition has published policies on transgender and sexual orientation equality, but nothing on sex-based equality. It is a matter of their policy that transgender individuals must be addressed by their stipulated names and pronouns. To do otherwise falls under their (Stonewall's) definition of transphobia. They also encourage people to use the facilities that best fit their gender expression. I would expect the latter statement, at least, to change.
I know of another institution who posted in horror after the judgement in full support of their trans staff, but saying nothing about women. They have suggested they will revise their policies once EHRC guidance comes through, but in the meantime here are numerous sources of support for trans people. No supporting words, absolutely nothing, was said in support of women. This material was posted on their staff intranet and is not in the public domain.
You have to think, surely, that the cases involving NHS Fife and the Darlington nurses will fall flat on their arses after this ruling, albeit the law hasn't changed in the slightest but has merely been clarified - as if that was needed. How can they not? But after the past few years nothing about this shit show would surprise me.
About to dig again in support of the Sarah Summers vs. the Sussex rape crisis case - who surely should be in a stronger position than she was on the day she started her action. It's taken a disgraceful four years for that case to be listed, with the one hopeful benefit that last week's ruling might help her arrive at a positive outcome.
In the meantime I think we need to be vigilant and keep digging in support of important cases like FWSs', Sarah's, and others. Like you, I don't think this is over.