For certain in that scenario (and maybe regardless, but definitely if they think he's a question mark) they gotta improve the backup QB position.
As I mentioned in another post, it'd be ideal if Dustin Vaughan had a great offseason, showed development and then had a really productive camp and preseason. Maybe he still wouldn't be ready to be the #2, but at least show enough so that they think he could compete for a starters job in 2016. Then you have a potential scenario where you have a talented, young, very inexpensive starter in 2016 that knows the system (whatever that might be) and wouldn't be a "rookie" trying to learn the ropes, all the while surrounded by a pretty talented young roster. If Vaughan isn't giving them good vibes after the season, peraps you spend a middle to late rd pick in April on a developmental QB.
Otherwise, if he (or other young guy) isn't the answer then 2016 you almost have to spend a 1st rd pick on a potential franchise QB