Buying out PLD would be pointless IMO.
Even at the favorable cap penalty, you still need to fill that role with an equal or better offensive player for the difference in salaries. Assuming Kopitar regresses over the next three seasons, odds are the expectations of PLD increase along with his icetime and meaningful offensive role.
He was without question a disappointment in this series, but he's a kid in his mid 20s with size and the pedigree to be an impactful forward.
If the goal is immediately improving, LA should focus on the area that has stood out the most over the last three playoff runs--their goaltending.