It is a possibility, but I wouldn't say it's likely. He's not the youngest player and I doubt many teams would give him more than what he can get at current max when he's 31 year old. He's entitled to 30% max now.
30% of 68M is about 20.4 with rising salary of 4.5% every year, that would be 21.3M second year, 22.2M 3d year, 23.1M 4th year(or thereabout). That's 4 year 87M contract. What's the chance he'd get a better deal after next year when he will be 31 and his level of play might even drop this coming year. If I were him, I'd take the max now instead of waiting for next year. Not many free agents get huge money at 31.