Granted, the teachers unions are the big dog when it comes to public sector employees, but they're hardly the ONLY public sector union in Colorado with employees covered by PERA.

As for "paying out massive amounts", what do you mean?  In high wages if benefits go down?  That just depends on whether they have a shortage of employees and applicants willing to work for the salary+benefits offered.  If demand outstrips supply, then yes, they'd have to start offering more.  But if those jobs continue to be filled, then no.