First: do the buyers want you out? Maybe they want tenants. The eviction would be coming from the seller side and they could be doing that sort of pro forma.
Second, if the answer to that is "yes" find out when they want you out. My guess is that they want to keep the rent flowing as long as possible and, for insurance reasons, want to keep someone in there until right up to the closing. So you need to find out when it will close and plan accordingly.
But if you find a good rental, grab it - unless they want you to stay on of course.