I think you can get a little more for Patches.

Find an alternative to Johnson.
Hansen signing I just don't get. Less so when you bump Hudon from the lineup.
Seabrook is a non starter. I'm not even evaluating the trade or judging Seabrook. A 3rd pairing RHD is not a need.

Johnson is a puck-moving option that is available to compliment Jeff Petry. He's a player you'd be able to snag on a short-term deal because he's going to be looking for a higher salary, which the Habs can afford to pay. He's a different breed than Alzner, who's been a flop.

Hansen could be done without, but he's a decent buy-low who could bounce back in the East. He's a strong fore-checker, he has a scoring touch and can help out the PK.

Seabrook gets you Anisimov, who replaces Plekanec as your top shut-down center. This is the double-down move. Seabrook's contract is a deal-breaker for a lot of people, but if the Habs can limit his minutes, they'll have three legitimate options at a position that's very difficult to fill effectively. Bergevin has done a bunch of half measures on his defense since the Weber trade--this is a full measure--you'd have a real defenseman on each pairing for the foreseeable future. You have Carey Price--he shouldn't be average--your defense should help him out a bit.

Maybe, maybe not. Kyrou is probably the best player in the OHL this year--him or Thomas. Add a first to one of them and I think that's the ballpark you can expect for a year and change of Pacioretty.