If he does survive this, his chance of being a "vegetable" is high related to he was down for 9-15 minutes without oxygen. It is possible he could remain in the state he is in for a while and it would definitely be a MIRACLE if he came to and started talking, etc. It is a wait and see situation at this point.
Keep us posted.
Sounds to me like God didn't intend for it to be your father's time to go whe he was taken off life support! I hope they are giving him some oxygen at least to aid in increasing his oxygen levels?