I posted it on Reddit a couple days ago, but to me I think his best case scenario is...
One more season in Finland. He needs to physically fill out a little more, he's not really small or weak, but needs some extra mass to be at his best when he gets here. Also needs to prove that he can regain his edge and not be scared of the injury. Plus he'll have a list of things to work on from the Preds staff after development camp.
Then come over to start in Milwaukee, adjusting to the rink, pace and physicality. Once there we hope he lights it up and earns a call-up from which he's never sent back. Trigg has been pointing out for years here that the top NHL wingers rarely spend more than half a season in the AHL. So it's a really good barometer for judging what kind of NHL player they will be.
So that's like 1.5 seasons if everything goes right. It's not a lost cause if he takes longer, but that's really the timeline that we should be hoping for.