Quoting: TheAlien
That Doughty contract is gonna be a problem soon
No it's not. The Kings aren't going to have any contract problems for 5+ years.
They're currently sitting nearly $20M under the salary cap, and aren't going to be adding any big money contracts this season (they might spend a couple million on a UFA LHD). Next season, they have a couple RFA contracts that they'll have to extend, but no one who will require huge raises. The only player that might get a decent payday is Alex Iafallo, but we're talking $4-5M. They'll still be $10M+ under the cap.
Then July 2022, both Carter and Brown's contracts will be falling off the books, freeing up an additional $11M. Kempe and Vilardi will need extensions, but it's unlikely they'll combine for more than $11M. Petersen will also get a new contract, but again he won't get more than a few million, as the plan is to transition the starting role from Quick to Petersen slowly over the next few seasons. 2022-23 is the first year that the Kings might actually look for some UFAs to help. They'll have tons of salary cap space available to enlist that help.
July 2023, Quick's contract is up, and he'll be replaced on the roster by Ingham or Parik, either of which will have a six-figure contract, so that's another $5M you can add to the bank. Madden's ELC will be expiring this season.
Finally guys like Turcotte, Kaliyev, Byfield/Stutzle, Thomas, and Dudas will be ending their ELCs in 2024, but Kopitar's $10M falls off the books that summer. They'll probaby re-sign him, but he's not going to get anywhere near the $10M he's making now.
TL: DR; The Kings current salary cap situation is ideal, and unless they go out and shoot themselves in the foot with an untimely and ill-advised UFA signing, they're likely not going to have cap issues until the last season or two of Doughty's contract.