Odds are that's probably true. But, everyone said the same exact thing before the Rangers made their run to the Stanley Cup Final in 2014. That they weren't ready, they aren't going to get past team X or Y. They should have sold at the deadline. They're just getting experience for McDonagh, Kreider, Stepan etc. And then they went on to the Stanley Cup Final and then won the President's Trophy the next season and got to the Conference Final and were one win away from back-to-back Cup Final appearances. And then their window collapsed as quickly as it opened.
So, we don't know what's going to happen. IMO, there's literally no point in having Zibanejad, Kreider, Panarin, Copp, or Trouba if the goal here is to simply gain experience. They're here to win the Cup. This team has a legitimate shot and IMO they're a better team than 2014 and 2015. The goal should be to win the Cup until it's time to strip it down and rebuild again. You don't know when your window will present itself or close itself.
I feel this is an advantage to Lafreniere, Kakko, Fox, Miller, Schneider, Shesterkin, etc. Is that they are growing in a winning environment where winning is the expectation. Unlike typical rebuilds where teams are perennial gutter teams.
It's my opinion that the team is ready now. And they should strive to continue being ready for a few years. This leadership core won't be around long. The young guys will be here long enough for more than one iteration of a contender like Kreider has been. But Kreider, Zibanejad, Panarin, Copp... they won't be.