You assume that nothing changes in the K12 business model.  But is that realistic?  In higher ed we have seen much more use of adjuncts. Why not in some parts of K12?  And technology? And moving from seat-time to competency-based?  

More fundamentally, there is a huge chicken and egg problem here. In many other locations where teachers make (much) more money, the increase in pay was the result of many other changes (e.g., curriculum reform, elimination of grading on a curve, activity based costing, more integrated supports for at-risk students, faster removal of ineffective teachers) that led to better achievement results. Better pay (and more respect) was a reward for better results.

Yet here in Colorado, the teachers union demands higher pay and tells taxpayers to trust that it will produce much better student achievement results.  Unfortunately, taxpayers have heard this line too many times in the past, and can see the lack of results past pay raises have produced.