Thornton is a big risk. Playoff performance, age, cost, declining production, etc.
As long as the contract reflects those factors it might be worth taking a chance.
At $6.5M for 2 seasons, I'd rather stay away.

Alzner is going to be vastly overpaid for what he brings. Not sure that contract is going to be in the realm of consideration.
He's also a shutdown defender where we are more in need of a mobile puck-mover that can contribute on the PP after the departure of Beaulieu.
Another player I'd prefer we avoid.

If we deal with Carolina, I think it has to involve Staal or Lindholm, with Hanifin as a secondary target.
Staal is probably more likely to be dealt, and could be useful, but I'm not sure he's much of an upgrade long term over Danault.
Right now he would be an upgrade over Plekanec, but for how long?

With all of that in mind ... I could see Bergevin making these moves, so I don't think it's unrealistic.
Calling up Hudon might be the most obvious flaw there, as Bergevin seems to be determined to keep him in the AHL.