Well we call Byfield a "Kopitar replacement" but even Kopitar took a couple years to become Kopitar under Terry Murray. On top of that, I feel due to his age and accomplishments (or lack thereof on the world stage) Byfield is 2+ years away from the Kings. So that means he's likely four years away.
On the other hand, we don't necessarily need to "replace Kopitar". We've had Kopitar for years now and missed the playoffs. What we need is to bring in a new 1-2-3 center punch for today's NHL and we may have that in the kajillion nice center prospects we already have in Vilardi, Turcotte, JAD, Kupari, Thomas and whomever else emerges. Center is the last thing I'm worried about. I'm looking at LHD and to a lesser extent the goaltending pipeline behind Petersen and that's what I think we need. Do we need to draft to fix this? Not necessarily cuz UFA/trading, but them's the gaps I see.
Four years away from replacing Kopitar or making it pro? Because if you look at recent #2 picks... Kaapo Kakko, Andrei Svechnikov, Nolan Patrick, Patrik Laine, Jack Eichel, Sam Reinhart (should've been Draisaitl), Aleksander Barkov... that's a pretty top notch class of talent.
So you go back to forcing yourself to take a position of need in the present rather than take the best available player? So if you had a choice between Aleksander Barkov or Derek Forbort, you're going to go with Derek Forbort because of immediate need?
The Kings do have some decent goaltending prospects and left handed defensemen in the pipeline. I don't know what your concern is, but your dismissal of Byfield seems rather silly based on a bunch of unproven prospects who may not even make the NHL or transition to other positions (or get dealt to address those needs you're concerned with).
I'd rather gamble on the best talent available than address a need, which would be a stupid thing to do at #2, like selecting Hickey fourth overall.