It's not 100% that whoever gets #1 is taking Lafreniere. There are a lot of teams, including the Rangers, that are in need of a potential 1C and Byfield literally checks every box you want. Brooks already wrote about how is the Rangers get the #1 pick it would not be a slam dunk for Lafreniere because of Byfield and what the team needs.
Looking at the three teams that are out: Rangers, Jets, and Panthers, I'd argue that both the Jets and the Rangers need that center. The Panthers have Barkov, so they don't and are potentially losing Hoffman and Dadonov this offseason. Laf would slot into their top 6 by the end of next season, if not earlier than that. Winnipeg has tons of wingers already and beyond Scheifele, they do not have much. Roslovic has underwhelmed.
The teams down 2-1 in their series: Pens, Oilers, Wild, Preds, and Leafs. Leafs, Oilers, and Pens would take Lafreniere, they have their top 2 centers. Wild desperately need a 1C and have Fiala, Kaprizov, Donato, Greenway, Zucc, and Parise. Sure, one could slot on the 4th line, but outside of Boldy, no center prospects. Preds probably take Lafreniere. They have a ton invested into their centers, not much in the pipeline, but beyond Forsberg and Arvidsson, their wingers leave a lot to be desired.
For the teams that are up 2-1: Columbus, Montreal, Arizona, Chicago, and Vancouver. Vancouver and Chicago would go Lafreniere, both have young centers that were high picks with Toews and Horvat having their roles on the team locked in. Montreal probably should take Byfield, but their fans would riot if they passed on Lafreniere. Arizona and Columbus probably take Lafreniere. PLD needs a running mate in Columbus. Hayton was taken #5 a few years back and they have Schmaltz and Dvorak locked in as a C for a while.
Lafreniere: Panthers, Pens, Oilers, Preds, Leafs, Columbus, Arizona, Chicago, and Vancouver
Byfield: Rangers, Jets, Wild, Montreal (but they won't)