Based on what? Larkin is waaay ahead of Zetterberg at the same age.
Zetterberg didn't crack the NHL until he was 22 year old, in the bottom six, albeit on a stacked team. Larkin cracked the NHL when he was 19 years old, as a top line forward, albeit on a bad team...
Larkin, to this point (age 23) has played 389 games, and has 266 points (0.684 points per game). Zetterberg, at the same age, had played 140 games, and had 87 points (0.621 points per game).
Zetterberg didn't break out until he was 25. Larkin is currently 24, poised for a breakout, after a down year. By the way, that down year that Larkin just had, 53 points in 71 games (0.746 points per game), Zetterberg had 43 points in 61 games (0.705 points per game), at the same age...
Zetterberg was never on a bad Red Wings team until the last couple years of his career. Every other year, the team was considered a legit contender. Larkin has never really been on a good Red Wings team, and hasn't had close to the same supporting cast around him.
Zetterberg was never expected to be "the guy", again, until later in his career, after all the future hall of famers had retired. Larkin was immediately expected to be "the guy", (captain or not), as soon as Zetterberg retired.
I'm not going to say Larkin will have a hall of fame calibre career (he could when it's all said and done), but to say he definitely won't, or that "he will fall way short of Zetterberg", at this point is dumb...
And you rag on me for calling a 4th line winger (who is older than Larkin) "replacement level"... LOL