Not saying you are wrong.....but the opposite can work as well, see San Jose with Thorton and Marleau. Also worth noting Sakic himself basically left the Avalanche at one point, and only after that really became a legend with the franchise. Point being, if the asking price is not met, the two sides may be forced back together for a time....but maybe find their way in the process.
Don't get me wrong, I think Duchene is done here. But if he survives the deadline, he gets a bit of a breather and maybe has a bounce back final quarter of the season. Team starts playing just a bit better with the pressure off and the guys start to have a little fun. Avs move into the summer and another deal is made, maybe being Lando, maybe being with the 1st overall pick. (I could see a world in which the Avs move the pick, not one of Lando or Duchene) That move brings the needed D man in. A few smaller moves round out the forward core and Sakic tells Duchene he is not going anywhere this summer. New coach, again, a vet with some presence in the room. Team starts next year as a middle of the rung team, not terrible, not great. Duchene, maybe still a bit raw over it -- starts to settle into a grove. The Avs do what we hope they do, and hang around the 6-7-8-9 spot out west. Matt has a good start to the year and he and Mac settle in as a 1-2 punch down the middle. Varly stays healthy and the team is in playoff contention at the deadline. Team does not trade Duchene then either..nor do they make any other big moves. A strong playoff push gets the team in and they push a top seed, maybe winning maybe losing. Team adds a bit more via the draft and UFA, go into the next season and actually step forward as a franchise. Once again the deadline is largely unspectacular, adding a small piece or two. Team makes the playoffs, wins a round and feels good about the next year. The next wave of prospects start hitting and there is a positive attitude around the franchise again and the new coach is someone Duchene likes and trusts that has helped rebuild his game....... and so on.