Will my grandfather remember us?

On Saturday, my 82-year-old grandpa fell and hit his head against a rock. He was unconscious for about 3 minutes, when he regained consciousness he seemed normal except for a slight bleeding wound on his right temple and a bit of confusion. After two hours, his condition began to deteriorate. His symptoms made me suspect that he had a subdural hematoma, and we rushed to the nearest hospital (about one hour and a half away). Indeed, he immediately underwent a craniotomy because he had a subdural hematoma and blood was beginning to create too much pressure in his brain. It's been 4 days already and he has surped all expectations by surviving. His speech is slurred, he can move, but it's hard for his to move the left side of his body and he does not recognize my dad or anyone else for that matter. He remembers small things like the date of his wedding and how many years he's been married. My question is, will he remember us eventually? Or is the damage to his brain permanent and incurable?