Those do exist, but as far as I'm aware the most common structure currently is that it's mainframe consulting companies and their consultants that command those

Those do exist, but as far as I'm aware the most common structure currently is that it's mainframe consulting companies and their consultants that command those salaries. Anyone in an actual employee position I've never heard of making above 100k/year. I have a friend who went from being the form to the latter and immediately doubled his salary, despite the consulting firm making it clear that he was at the bottom of the totem pole, despite his being 5 years or so into mainframe work.