I think that's how most teams get built in a lot of ways...you rarely have a team that's just like "ok here's everyone and they're gonna grow up together and all be developed and ready at the same tiem"
it's a mix of new players, older players, vets, etc. The trick is to get the right pieces into the right places at the right times. The Rangers have an intriguing mix but they have a year or two to really fill the major holes sufficiently in order to take full advantage of Zibby and Panarin's (and Kreider's) best years while also allowing for their hopeful young stars like Kakko, Fox, hopefully Laf, to develop enough to contribute on a consistent basis. Then you hope you're a contender. Then you hope as the older guys decline, the younger stars are picking up the slack, and you're filling the holes with more new draft picks etc.
So, big thing in my mind is just how the Rangers fill some of the bigger holes they have and that includes a functional fourth line