The varies a bit depending on the kind of dance, but, yeah, people who can stay in dance much longer than that (and, really, people who can make a decent living in it at all, even below that age), mostly do so as dance instructors, choreographers, etc., with their own dancing (if its even something they directly get paid for at all) sort of an adjunct and means of advertising the other parts of what they do.
There's something much weaker in technology (not just in computing) in the worker -> manager push, where people who don't jump that divide by a particular time start being seen as less desirable as workers. But its brutal in dance (and only partly due to the actual physical requirements of performing the movements.)
It's amazing if you can even live as a dancer. Usually, there's a second job. (I worked in CS in parallel to the dance thing. And at some point looked at the pay checks :)
I am curious, did they need to retire because they no longer possessed whatever it took to dance, or was it because people in their industry assumed they no longer could, or simply because they needed a more lucrative job?