The defense is what is going to hold the Avs back from winning anything with this roster...if they had a good defense, they could fix the forward group with prospects, trades, and smart free agent signings. But the defense is just a disaster, and that can't be fixed via trades - not without completely decimating the forward group (and that's still a big if), and then you have a forward group that can't be fixed...
They've apparently been trying to fix this defense for years - in on Orpik and Stralman (heard something about Niskanen too), going after Kulikov, offering Landy for Lindholm, heavily interested in Trouba, going after Sekera, signing Beauchemin, etc., and they've failed. It's time to admit that and accept the inevitable.
There needs to be a re-tool, and a proper defense has to be built. Keep EJ, keep developing Zadorov and Bigras, and everything else has to be reconstructed from the ground up. Barrie would do really well on a team that lets him roam and has competent defenders around him - and I actually thought the Avs could do that this year - but with Beauchemin not even being a second pairing defender, EJ injured, etc., it's apparent that Bednar can't / won't let him roam, in large part because the rest of the defense is so bad they can't afford to let him do that. It's unfortunate, but Barrie needs to be replaced. He should be on a team with three established top four defensive defenders and a proper top pair, e.g. Edmonton with Sekera, Larsson, and Klefbom, that can afford to let him exploit his talent. He won't have that here, and by the time the Avs can provide that, Barrie will probably be 1-2 years from UFA. I'd move Barrie, Duchene, and possibly Landeskog (if the right deal for a top defender comes along), along with making available all of the garbage pieces.
Losing Duchene would be miserable. He's the only forward who's working right now, and trading the one guy who is working and loves the team would be a damn shame, but sentiment doesn't have a place. The team sucks, they aren't winning anything right now, it's time to build a new future that Duchene, unfortunately, realistically can't be a part of - in part due to his contract and age, but mainly due to top levels assets being required, and Duchene moving is one of the best way to get those assets.