If real estate market continue drift down, assume the house was now worth 100k and the renter (leasee) move out, then the property would fall back as a rental unit and owner is under water..
There are several ways to continue this:
1) keep marketing it as rent to own
2) rent it out
3) sell it
There are several ways to continue this:
1) keep marketing it as rent to own
2) rent it out
3) sell it