It is a problem systematically already, we’re seeing women be pushed from top ranks bit-by-bit. In Chicago, trans women won gold and silver for a biking event. This is going to continue to happen, especially if what trans people are saying is true and there are many more trans people who will be coming out and living how they want.
Trans athletes can compete with biologically-aligned people of the opposite sex in trans-only events, which should be a thing for each sport. This is by far the easiest, most rational decision that doesn’t stomp on biological women. Trans men take testosterone, and trans women take estrogen. Let them either compete in the men’s division or against each other.
What, exactly, is “untenable” about opening a division for them?