WCS isn't worth chasing, but if he's willing to stay and not demand more than he's worth (which isn't likely since he's constantly talking about money), then let him walk. I can see him in a Noel situation where he declines a reasonable extension in the hopes of a big payday, only to find that the market just isn't there for him.
There are, however, solid big men free agents to consider that can actually rebound that the kings could give that money to:
Nikola Vucevic
Jonas Valanciunas
Comparison to WCS (Basketball-Reference)
Those two guys rebound way better despite WCS's athletic abilities. WCS runs well in the space and pace that the Kings play, but if they want to win playoff games, they will require a center that can rebound the basketball and defend the rim.
Guys like Marc Gasol, Al Horford, Whiteside, Deandre Jordan, Kanter, etc are also on the market and there aren't that many teams with cap space. The Kings have a good shot at getting Vucevic or Valanciunas IMO.
Darkhorse candidate to replace WCS is
Julius Randle. He's primarily a 4, but he can still rebound well for his size and is tremendously better than WCS on offense. A rotation of Beli/MB3 and Giles/Ju off the bench is insanely talented.
Yogi
Bogi
Burks
Giles
Randle
That second unit is actually damn good.