I think my concern with this plan is how quickly are those top drafted young guys going to be ready to contribute at a level that makes them legitimate "core" pieces? Even with #1 picks, it tends to take 2 or 3 years for those guys to really hit their strides in the NHL.
Even if you assume the Penguins get lucky and hit a #1 pick in 2026, that leaves you with say Frondell in 2025, McKenna in 2026 and let's say another #5 pick in 2027. Is that plus Crosby and their current prospect pool enough to make a competitive team? I don't think so, and that even assumes Crosby will be back for the 2027-2028 season.
Malkin is retiring by then, Letang is declining more and Karlsson and Rakell will most likely be traded. Even if Crosby is back, I still think this team would be a good bit off from a playoff team with McKenna, Frondell, another top-5 pick in 2027 and their current prospect pool.