Hendrix has potentially
36 games left in his Irish career if he ends up back for a 5th year.
If Golson gets hurt this year, Hendrix may be the starting quarterback. If Golson gets hurt next year, Hendrix may be the starting quarterback. Kelly has even said himself that Rees would be the short-term answer as the backup (i.e. a late-game drive or taking over if we need to go pass-heavy hurry-up), but Hendrix is the best suited for taking over the entire offense if Golson were to go out.
In case anyone hasn't noticed, Golson is 5-foot-nothin', 100-and-nothin'

No one knows how good Gunner Kiel is going to be in spring ball next year or at the start of next season. Hell, no one knows how good Hendrix is
right now. I also think there are packages in the playbook for Hendrix that we haven't even come close to dusting off yet.