If the owner is selling by way of a short sale, you should ask for a Discounted Rental rate until the home is sold. It doesn't look good for the owner presenting his hardship case to the bank when he's still collecting Full Rent but not turning around & making his mortgage payment.
You will be asked to show the apartment to potential customers during this period. It would be in your best intrest to make sure it is presentable. You will either be having a new landlord or your current land lord will have to buy out the rest of your contract provided it is in writting. Either case you should cooporate for the sake of getting a referanc in the future or you may be meeting your new landlord and relations are made by first impressions.