Sacramento would need WAY more
They won't get much more for a guy who hasn't been able to get his team to the playoffs and is widely considered to be a headcase. Consider that their average record since he's been a King is .344 and he has only led them in wins hares twice in his 6 years. Isaiah Thomas managed that feat in half of the time.
They are getting a guy you can flip for a 1st in Bradley, as well as the #3 overall pick and a likely top-5 pick next season. Add in the high 2nd that some GMs prize above late 1st for their lack of guarantee and I think that is a handsome value.
Do you think the Lakers would trade Randle, the #2 overall pick and their 2017 pick for Cousins? Oh wait they can't, they don't own their pick unless it's in the top-3.
I don't see someone throwing them multiple top-5 picks and players of consequence for Cousins. I'm not even sure I'm giving up the 2017 pick swap for a guy who has 2 seasons left on his deal and will almost assuredly leave the Kings dumpster fire come summer 2018.
Obviously he's a great player but he's not on the level of Durant, Lebron, Curry or AD. He's a tier down with guys like Butler, Aldridge and Griffin.