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?
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.