If Gaborik completes his medical, he needs to play to earn his pay check, just like you would need to go to work. Gaborik isn't unable to play because of injury, he's just bad at it and gets injured frequently. This isn't a case of a guy walking away from 10 mil when he could just unofficially LTIRetire, it's a guy that needs to play to get a pay check.
As for specific examples, the best I can come up with is John Urschel, and while NFL contracts aren't guaranteed like NHL deals, he certainly wasn't expected to get cut anytime soon. He just decided he earned enough and valued his health more than more money. Jason Worilds was considered one of the most sought after free agents when he retired, so while he was technically without a contract, he'd have had no issue getting one, and left lots of money on the table.