Fred wrote.......

"What would happen to a WSOP players chips if he had to withdraw for a health issue or family emergency?"

Whatever chips he had would be blinded off until there were no more chips left. There are no refunds for any reason once a poker tournament has started.

"If he currently had $5,000 in chips could he cash them in or is he out the entire $10,000. "

You can't cashed in tournament chips as they are no cash value chips.

"Could he have someone "sit in" for him?"

No, not under any circumstances. Andy - Las Vegas