I agree - and that's not even a speculative possibility either, they've already started out in the open for everyone to see...
Look at the Olympics, they used to (without any issues) only require trans women to show 2 years on HRT in medical records, and a recent blood test showing hormone levels within average cis women ranges... Then after Trump and co, now that was scrapped. Now, they test for the SRY gene (a test that is widely condemned as disproportionate). This means anyone who has the SRY gene (which as far as I'm aware only activates once in the womb, and is what causes the development of male genitals) is immediately disqualified from taking part in women's sports
This obviously targets trans women regardless of hormones and medical history, but also targets any cis woman who is found to have the SRY gene. It's rarer, sure, and terfs would argue that can't happen with their basic biology they learnt at 6yrs old... But it is possible for the SRY gene to translocate from the Y chromosome onto an X chromosome in the womb... Causing a cis woman who grew up her entire life as a woman with no difference in sex characteristics, with XX Chromosomes, to be found with the SRY gene even if it never activated during development... And the Olympics even recognised this, and just shrugged their shoulders. So in the eyes of the Olympic rules, they don't even consider cis women who may have the gene (and be unknowingly intersex) to be eligible women. All for the sake of "fairness"
Honestly, I feel as though if we just mandated that everyone should have to get a chromosome test, there'll be so many cis people who find out that they're intersex that the whole culture war aimed at trans people falls apart because they no longer can stand on the pedestal of "the majority" and become so much more aware that sex and chromosomes aren't as black and white (or bio-essentialist) as some may think...