Well forgive me if I'm asking you to repeat yourself but what about the sport issue?
You know what... I don't care honestly.
My best answer is "What ever is sustainable." Sports isn't going to the bathroom, it's.... not exactly voluntary but close. Sports (of the kind we're talking here) only survive if it is entertaining to watch or participate in.
We can kvetch and moan and pontificate and ponderingturtle can scream at pigeons on the sidewalk all day long about what's fair or right but if we modify sports to accommodate transgenders and in doing so we make the sports less fun to watch and/or participate in.... well then we won't have sports at all, transgenders included, and then who exactly won in that scenario?
Sports are an issue because it's all about shattering a fantasy we all sort agree to pretend is true, the idea that biological women can compete with biological men in statistically meaningful numbers once you average the bellcurve out.
We have separate male and female sports because we just sort of all know but... like just don't bring it up that women are less on average less physically capable then men. Tumblr can rant and scream about it all they want but a women's basketball hoop is shorter, women's Olympic swimming pools are smaller, every single record that objectively measures speed over distance, weight lifted, object thrown, etc is held by a man with like a... within the margin of error few exceptions.
So men being competitive against other men and women being competitive against other women was, like weight classes and age classes and stuff like that, something we all just tacitly agreed was necessary.
The transgender movement's core philosophy of "Your gender is not your body" breaks that and we're all trying to find a way to pretend it doesn't and we can't.
That circle will square itself however it wants to because... it's sports. It's not essential. It's not a human right. It's not the tail that should be wagging the dog in this case.
Going to the bathroom and just generally living your life isn't a competitive spectator sports so... difference.