Corny jokes aside, this is definitely a big deal. Particularly after he'd assumed the reigns as THE guy midway through their season last year and went through Spring ball in that position, taking the bulk of the reps with the 1s.
So this on top of them losing the guys that they lost on defense puts them at a major disadvantage for the next 2 years or so.
Edit: and further, as it has been pointed out in other outlets, if this is due to academics, he can't get a scholarship ANYWHERE next season. So not only is this not good for ND's football team, it's not good for Mr. Golson either. Hate to see that.