This is a good question. I have received reports that U of D Police, is currently operating on Nextels. This would make sense, mostly because I have not heard any radio traffic from them on 453 or 800 MHz.
Since the city of Detroit moved to their P-25 TRS, the U of D PD, has for all practical purposes vanished. Since WSU just recently migrated over to the MPSCS, its very possible that the U of D will do the same in the future. This would place them on the same platform as DPD, and would go a long ways to promote interoperability between the two departments.