i do suspect at some point they will have to deal for a "star" if they want to compete for cups.
they got lucky this year and found patrick kane on the scrap heap and signed him for nothing. i doubt that happens in the future (or ever).
yzerman has said before that he'd rather trade for known players than draft picks. he has had a few years to build up the barren farm system and had done a great job of it.
i dont think they should be dealing prospects for rentals, theyre not at that point this year, but over the summer? maybe someone shakes loose like a tkachuck or kyle connor in winnipeg with their financial problems?
as you say, now they have the prospect ammo to go get them.