I have significant anecdotal evidence for this, though I wish I had a crystal ball.
With students, "less desirable" usually means kids who can pay a little less than the $1100+/bed being charged in the larger buildings. We're still not talking about significant eviction risk, or any more damage potential than normal. In fact, many of the students who avoid larger buildings are international, and tend to take better care of the units.
At the end of the day, though, there will always be upperclassmen who prefer an older house with fewer units. They have their own kitchens, they're living like real adults, access to a back yard, a front porch; all of these things will perpetually be attractive to them. The bigger problem in Ithaca is that property values are so high, there's not a lot of motivation (or financial room after purchase) for landlords to keep their units updated and nice. There's plenty of smaller multifamily student housing in Ithaca, but not much of it is actually decent.
All that to say: I don't expect all of this construction in Collegetown and elsewhere to wipe out the demand for smaller multifamily buildings. The problem is making the numbers work in this town!