I think that the way it is slated right now, ND plays each ACC team once overt three years. So if Golson sat out next year and played his last remaining year of eligibility the following year, ND would not face him unless in a bowl game (provided he picked NC).
Personally I believe that ND could meet with a lot of success next year implementing two QB's. It was a disaster under coaches like Weis, but Meyer utilized it to great success at Florida 10 years ago and even Kelly did the same at Cincy 6-7 years ago. Golson can still see a lot of playing time next year even if he's not an every down starter.