Here are the two player Bergevin will trade before half the season in my opinion.
Matthieu Perreault

The forward is injured but could return in a few weeks. Perreault has four points and a hat trick for the Habs thus far this season. Expect other clubs to call closer to the deadline. A cap hit of only $950,000 benefits the 33-year-old prospective free agent.

Like many Canadiens, Lehkonen is having a difficult season. Currently, this player has one point in 10 games and 41 points in 127 games. That $2.3 million threshold won't cut it. Lehkonen should be replaced by one of the Canadiens' young forwards. Playoff clubs seeking for a checking winger will be monitoring the former second-round pick.
Also read on Hockey Patrol :
Maple Leafs reporter addresses rumours of Mitch Marner's trade list