I think it's simple, with Read and Couts out, do you match the Giroux line against the other team's best line and sacrifice your best offensive line (and Giroux isn't a great defensive center, nor is V a great defensive forward) or use PEB and hope high energy will slow down the opposing line while the G line gets a more favorable matchup.
Schenn and Cousins are simply bad matchups against offensive lines.
I can't imagine why Hakstol would trust VdV in a defensive role over Luby right now, I mean Luby has tons of NHL experience, oh, he doesn't? Same with Weise, he's big, pretty fast and experienced.
Luby and Leier will have to work their way into the coach's trust the way Provorov did, Konecky still is held back from tough matchups, but is gradually getting more responsibilities. You'd also want them with a more talented and more experienced center than Cousins, but who right now?
Laughton is an example of a physically talented player who isn't mentally ready for a significant role, everytime he's been handed that opportunity it's been a fail, or at best a "meh."
They are deeper, they just lost 2 of their top 9 forwards, that usually presents a matchup problem unless you're really deep. Next year guys like Leier and Luby will have some experience, Lindblom is a good bet to make the team. Depth is evolving.
As far as a deal, I doubt Hextall wants to take on salary, he's just getting out of cap hell and I think never wants to revisited that place. So we're talking Schenn (hope he gets 60 points) for a solid center or a young defenseman plus MacDonald's contract - and no big FA signings. He's not dumping Streit and Schultz and then picking up a $5M a year contract for 5 years and being cap constrained from now until eternity.