Come on now. Don't spit the bit on this one. He's good, and doing well, but 23 is not exactly Kobe out of HS, and he's not going to be a substantially different player in 5 years. He'll be like he is now, with more experience.
Just for fun, when Steve Nash was 23ish he was in his second year in Phoenix (first time) averaging 9.1 PTS, 3.4 Assists, 2.1 Rebounds, 1.3 TO's and shooting 46%, 42%, 86%. True it was in 22 minutes, but...he didn't hit his strides as a PG until he was 26+.
Nash is now 38 and averaging: 14.3 PTs, 10.5 Assists, 2.6 Rebs, 3.6 TO's and shooting 56%, 43%, 88% in one of his worst statistical seasons in 10 years.
Or there is Kyle Lowry who at 23 averaged 9.1, 4.5 and 1.7 TO's in 24 minutes a game and now is at 15, 7.6 and 3.2 TO's in 35 minutes.
Or Calderon (not in NBA at 23) Rookie year of 5.5, 4.5 and 1.6 TOs
Or Tony Parker who had 5.8 / 3.1 at 23 but is at 7.6 / 2.4, A/TO now.
PG is a position you can def learn and get better at, especially when it comes to A/TO.
Lin may not get substantially better statistically and I expect his PPG to dip from this 6 game stretch but he can become a substantially better player. He has a number of aspects to his game he can work on: 3PT shooting, TO's lead the way.