Selectivity for OOS students is also very high at Michigan. This year the OOS admit rate was right around 20%. Michigan gets about 50,000 applications a year, roughly 40,000 of them from OOS applicants.
I believe UNC Chapel Hill’s OOS enrollment is capped at something like 18 or 20% of its student body. UVA has limited its OOS enrollment to about 35%, but whether that’s a university policy or a legal requirement I’m not sure. Michigan isn’t subject to any such cap, and its OOS enrollment has gradually drifted upward, with recent classes upwards of 40% OOS. The state legislature has no say in the matter because under the Michigan constitution, the university is an autonomous, self-governing body, headed by a Board of Regents elected directly by the people. I’ve heard that the Regents intend to keep in-state enrollment at or above 50%, but that leaves substantial room for growth in OOS enrollment. I’m not sure meeting full need for OOS students will cause a big spike in OOS applications, though it could. I think the more immediate effect would be a dramatic increase in OOS yield, which of course would then allow the university to further ratchet down its OOS admit rate while further elevating SAT/ACT medians, etc.