I think Kerry Louise once retired from escorting and came back pretty quick, so might happen again - +1 for Sarah Lou as well.
I think Sandra Romain is quite often listed as escorting via photogirls? But people seem to have mixed experiences of that site so ... speaking of photogirls, they once suggested they had Jilly Kelly and Houston doing a 2 girl at once, if legit I wish I'd had a bang on that.