I'm fairly comfortable in saying that Ottawa has every intention to re-sign Duchene, Dorion has already alluded to having a good relationship with his agent. As for Brassard, I said it the day the trade happened but I've always viewed him a stop gap. That summer they also drafted Logan Brown who is a highly skilled centre, with Colin White comping off a great draft+1 season. I don't see White as stepping in as a 2C anytime soon but Brown certainly has the skill set to and had a good training camp. Chalpik is another possibility, had a relatively disappointing draft+1 and management wasn't shy in telling him how they felt. He came back and had a great final season in junior and has looked good to start the season in the AHL, I've always thought he would convert to LW but watching him play C in the minors he is a solid option. There's also Pageau who ideally is a #3C but has shown an ability to rise to the occasion when needed, see post allstar 2015/2016, but I'd only view him a a short term option if the younger guys need an extra year or two, he shouldn't be the long term solution.
Thats the sort of context that is often left out when outsiders evaluate trades. In just a value sense sure you can argue that Ottawa lost the trade but teams don't make trades to get value for an asset, it's about making the team better. In the short term I think Ottawa is a better team whether or not this trade harms them in the future will be the deciding factor in regards to it being a bad trade for Ottawa.