I guess they could, but the profit and operational model is completely different.
Rental requires longer term profit model, and the unit will need to be operationally easy to maintain for the long run. I lived in a few rental condos (eg, Concert) before, and in comparison to the non-rental units, there are actually less problems in rental units but the finishes are not as high quality. Rental lobby also tends to be less luxurious as well, and more importantly, you need a rental office and more in-house staffing - rental volume has to justify these resources.
Anyways, all I am saying is that I don't see it being that simple to switch model halfway.