This proposal deserves praise, but I wonder if it is affordable over the long term through economic downturns.
Perhaps it would be wiser in a financial responsibility sense to fund just the first two years with only minimal qualification (such as a high school diploma & state residency), then fund the remaining two years at four year colleges & universities only for those who have earned a stipulated minimum GPA and/or to those who major in certain needed areas.
I suspect that New Mexico is at or very near the bottom of educational preparedness for college. If true, then maybe the money would be better spent on pre-K programs and on improving the state’s public high schools. Possibly, by limiting the free college to the first two years & the second two years only for needed majors, then New Mexico could propose a more comprehensive educational initiative. Tossing an unprepared student in to a college or university may adversely affect the student & the quality of the college or university.