Since we're talking about the Sharks anyway, this is exactly how they made their last big playoff push. Thornton and Marleau in their mid 30's (Ovechkin and Backstrom, obviously), then the Couture/Pavelski wave (Kuznetsov and Vrana), and then a sudden boom of 20-22 year olds (Hertl, DeMelo, Donskoi, Tierney), all built around a core of 28-32 year old defensemen (Braun, Burns, Vlasic).
If you have to gamble anyway (and the nature of adding assets is always a gamble), gamble on your own young guys taking steps. If the window does close early, you always have the option of selling their primes for additional assets and jump starting your next window. If you're right, you already have the pieces for your next window instead of a bunch of guys ready to fall off a cliff or go find bigger contracts.