Guaranteed money is not as important as you think. Players will want a portion of it guaranteed to protect themselves against injury, but if you don't get injured and you play well - you'll see that money.
Look at Peyton Manning's contract with Denver for example. He's now 3 years into the 5 year contract. Each of the next two years he has a base salary of $19m (not guaranteed) and a cap hit of $21.5m Only a $5m cap hit to cut him.
If he wants to play next year, he will. And he'll earn $19m in the process - unless the Broncos restructure and offer him more. If the Broncos decide to cut him, fine. But another team out there will pay him the $19m he wants. He sees every penny of his contract in the end - the only real change to these contracts when they restructure is the timing of earnings