If we are talking purely on the "ceiling" of players...
Sproule and Lockhart both had high ceilings, hell, throw in Swankler and Fowler and Campbell and where did they end up? Sproule killed it after being traded, Lockhart is having his best start to date, Campbell through some unfortunate reasons and also lack of development/performance was let go. Swankler and Fowler for all their talent and high ceiling were purportedly locker room cancers.
You can have a high ceiling and not develop as is an obvious flaw in recent seasons with our organization and at that point, yes you need to try new things.
40 games in, who knows where we will be but again, if we are sitting in 4th place Molnar will find a new line because it is obvious the players are playing well together. Now, if we are 40 games in and the team is 12 - 26 - 0 - 2 or we are fringe playoff then yes 100% shake things up.
First and foremost he has to commit here. All signs indicate he will and that would be step 1. The sooner they bring him in, the more likely he gets top 6. The better lines 1 and 2 perform and the longer he takes to get here, the less likely they break up lines just because he COULD be good with a high ceiling.
Why not use Hartsburg? It fits the argument perfectly showing how chemistry > a single individal and may have been one of the few things he got right while here. He had 3 players, most of whom were average, maybe even below in the case of Sellan and Hoff and they played well above their skill level because of chemistry, you can't deny that fact.