Sakic has one big advantage: He's probably got 10+ teams interested. I believe one insider (McKenzie or Friedman?) mentioned 13 teams interested in Duchene at one point. And Sakic is probably the only GM in the league willing to sell a signed 26 year old top line forward for future based pieces. He can look at multiple options, other GM's wanting to significantly improve their club without losing big pieces from their roster probably can't. That does give him leverage over individual GM's, because he can always walk away and probably get a similiar offer elsewhere, they can't.
It will be particularly interesting this off-season I think if Sakic can't get what he wants now. The UFA free agent crop, assuming Radulov re-signs in Montreal, which I think is reasonable, is going to be abysmal. Obviously a few of last years free agent signings busted, but in terms of genuine top 6 forward talent entering free agency, you had Lucic, Ladd, Okposo, Backes, Eriksson, and Nielsen, then in terms of the more tweener variety you had Brouwer, Boedker, Perron, and then you had two talented reclamation sort of types in Vanek and Staal. This year, assuming no Radulov, you have Oshie, then a host of much older guys: Thornton (might easily re-sign), Marleau (ditto), Vanek, Sharp, Vrbata, Williams, Hanzal, and Bonino. I think there's a good chance two of those guys (Marleau and Thornton) will be re-upped by the Sharks, which makes that a very, very thin list in terms of genuine top 6 forward talent that isn't on its last legs.
If teams this off-season want to add top 6 calibre forwards they can't go money-happy and try to buy a solution, I think they will have to trade or stand pat - and some teams and GM's very well might not have the option to just do nothing. I think around the draft and at the beginning of free agency will be when there is a very high demand for what the Avs are offering.