How do you expect the colleges to change their budgets now that they will be making less tuition $s?
I would be happy to provide a buffer period, to adjust the nominal rate slightly upward, or to specify that the tuition cap applies only to in-region residents if you feel it advisable. Beyond that, it's worth noting that many if not most public colleges in Fremont already charge tuition ≤ $8,000 annually. CSU, for example, charges ~$5,700 a year for in-state residents (Source); in Washington, tuition for in-state students attending a public university averages at ~$5,200 annually (Source); in New Mexico, that number is $2,900 (Source). It is also true that the rising cost of college attendance can be traced, in part, to less-than-necessary spending projects that enhance a university's prestige in the eyes of college ranking publications, but have a negligible effect on the university itself (Source). In other words, it is possible for colleges to survive without charging in-region students exorbitant amounts. Furthermore, tuition is not the only source of income for public colleges; most of these schools also receive funding from state and regional governments, federal grant programs, and alumni donors. If these schools actually need more money, we can explore ways to increase any of those three funding avenues.
I agree with your arguments, but never the less a buffer period should be included so everyone has time to adjust. Not just the colleges, but also various programs that offer student aid. I'd say 6 months or a standard semester should be sufficient.