Dallas: Lindell
Montreal: Drouin
Montreal's spin: With the acquisition of Staal and the signing of Caufield, and the eventual returns of Armia, Kotkaniemi, and Toffoli, Montreal is going to have a glut of forward talent. With the injury to Chiarot, they have a huge hole in their top 4. Montreal could contend in the playoffs if they have a minute munching lefty who can play PK minutes. Lindell brings that in spades, and while 300K more expensive than Drouin, provides them a younger version of Chiarot, controlled for 5 more years. It would also allow Weber to take on less difficult minutes as he ages.
Expansion draft implications: Montreal would probably protect Lindell if they trade for him. But the forward spot opened up by moving Drouin would allow them to protect someone like Byron or Lehkonen, or Staal or Tatar if they signed them longer term before expansion draft.
Dallas Spin: Dallas is floundering. Yes they are still in the race, but they've only won 1/3 games this year. The loser points they've accumulated are giving them the illusion that they are in the race. They still might make the playoffs, but they don't have the offensive firepower to beat out two of Florida, Tampa, or Carolina in a best of 7 series. They need playmakers. The emergence of Jason Robertson gives them a taste of what it is like to have a true playmaker in their top 6. Drouin possesses that similar ability, and he might thrive in a smaller market. Losing Lindell hurts, but with Miro Heiskanen and Klingberg needing to be resigned long term, Dallas has the foundational pieces to build an elite top 4. They can resign Oleksiak, and allow Thomas Harley to get a look. Dallas would then finally have three lines that could attack, assuming their coach implements that kind of system. When Seguin, Radulov, and Hintz are healthy, lines could be Benn-Seguin-Radulov, Robertson-Hintz-Pavelski, Drouin-Faksa-Gurianov, Kiviranta-Dickinson-Dellandrea. A much more balanced and offensive attack.
Expansion draft implications: Dallas would have to protect Seguin, Benn, Radulov due to NMC. Droin, Hintz, Gurianov. This leaves the decision down to Faksa who has signed a team friendly deal, or Pavelski and his last year at 7mil. It would come down to exposing one of those players with Khudobin. The team could also choose to extend Oleksiak before the expansion draft, and then turn around and protect him. If Seattle takes Khudobin, he's replaced by Oettinger and/or Bishop, if Seattle takes Pavelski, he's replaced by Drouin, giving more youth, term, and 1.5 in cap space to be used to sign Heiskanen and Klingberg long term.
That's a lot of context, but this is a hockey trade that could actually make both teams feel like they won, if both players bring what they could potentially bring to both teams.