Seems like a lay up for the league office. The rest of the season it should be. With only 6 games left, it's an easy call. If it were week #2 some would be saying 6-8 games, some would say the whole year, would be a tougher spot.
Going into next season seems to much and too messy for the league. Garrett has some other iffy behavior and is also a premier player. I'm sure the NFL doesn't want this to be a huge story for too long, it's an embarrassment. They aren't going to let it carry over into next year. Rest of this season makes it perfectly clean.
Couple other notes:
Mason isn't totally innocent either. Even if a late hate after a rough game, he was digging at Garrets helmet, looked like trying to get it off, so I can't even blame Mile for ripping his helmet of Mason. Then after that Mason was still going at him, but there is no excuse for swinging the helmet at him.
Garrett got lucky! He connected hard with the helmet but Mason was unfazed and not injured. Can you imagine if Mason got knocked out with blood dripping from his head? It would have seemed 10x worse and Garrett could be facing a lifetime ban and possible real world assault charges.