The answer to this question is found in the contract. Typically, the transfer of the home occurs at time of "closing and funding" and funding normally occurs same day as the closing. So, if this is the case, the seller fades off into the sunset - hopefully with some money if there was equity in the home.
If there was a leaseback or some other transfer stipulations in the contract, then those would be followed. Otherwise, the seller is usually out of the picture and goes about the rest of their life after closing. Good Luck!