I think the big coup for the top six may be Sam Reinhart, a 25-year-old RFA who just scored 25 goals and 40 points in 54 games. He's had four consecutive seasons of 20+ goals and six straight seasons of 40+ points.
Tough to gauge what the cost will be to acquire him as he's also due to make a decent amount, having earned $5.2M this past season. What is that contract worth on a long term contract? And for those curious, his puck possession numbers have been strong on an otherwise abysmal team, so switching over to another bad team on the west coast shouldn't be a problem for him!
Given that it'll cost the team a few assets to acquire him, perhaps their second top six option can come via free agency. Given their experience playing in the Western Conference and on teams have often played the Kings, guys like Jaden Schwartz or Brandon Saad might be good fits as top six LWs.
A hypothetical lineup for next season if they land two of those names...
Iafallo-Kopitar-Reinhart
Saad-Vilardi-Kempe
Moore-Byfield-Brown
Lemieux-Anderson-Dolan-Wagner
This is assuming the team wouldn't bring back Athanasiou, given that he'll likely command more, and those dollars would be better spent on legit top six forwards as opposed to a guy who shows up in spurts.