I don't see anything wrong with your first suggestion; maybe there's no better use of the campus than as a park or some other municipal facility. Keep in mind, though, that Rider makes payments in lieu of taxes to the township, and those would be lost if the town itself took the campus.
The Lawrenceville School is on the other side of 295 and is actually a little further from Rider by car than TCNJ is. Why do you think the School is more likely than TCNJ to be able to make effective use of Rider's buildings and assets?
Waiting for the demand it be used for "Abbott" housing if it happens.

