We're not going to win anything with Larkin and RNH as our top 2 centers either.
At the moment, I see Larkin and RNH on par with each other. Larkin is obviously getting more ice time, as RNH is playing behind McDavid and Drai, (Correct me if I'm wrong) but that also means RNH is likely stacking up against easier matchups. Even if you give RNH a slight edge, Larkin's still younger and earlier in his development.
All in all, I think Larkin's development range is, at his floor being an adequate #2C to an absolute ceiling of being a legit #1C, with the likely scenario being that he ends up as a guy who can play as the #1 guy, but is really better suited as your elite #2 option. If he can be defensively great and put up a PPG pace like Bergeron, then he's absolutely a #1C, but I think he's gonna be more of a 55-70 point guy who's good defensively, much like ROR.
So likely the only way Detroit is getting that true #1C is in the draft. (And it wont be this draft) And then you have to consider that Rasmussen's target development is also to be a #2C. If we were signing RNH it would be one thing, but trading away assets for something you already have just doesn't make sense.