Since 1986-87, the first year I began watching the NHL regularly.
While losing Ceci and Broberg sucks, neither is what you'd call a difficult player to replace, based on individual value at present. I really liked Ceci, and the team got good bang for the buck from him (and apparently he was very popular with teammates, etc.), but with his slow puck-moving and so-so wins in board battles, he's theoretically quite replaceable. Broberg has potential to be a great puck moving / skating defenceman, but he's already 23 and hasn't even locked-down an NHL job yet. (St. Louis way overpaid for him, so let's hope he fulfills his potential for them.)
How to replace them? I've heard good things about Ty Emberson, and coach Knoblauch knows him well, so we'll see...
But, as I see it, the Oilers are definitely going to acquire 1 more experienced NHL Dman before the season starts or shortly into it. Maybe they're watiing for the Draisaitl contract to be signed before they evaluate how much cap space (if any) they have...
So, while I'm sad to see Ceci and Broberg go, it's not like they're irreplaceable. No, the two points -- as I see it -- upon which the Oilers' defense success or failure depend are as follows:
1) Mattias Ekholm's aging process. This guy is a really, really great defenceman. Like, if he were 24 instead of 34, I'd like the Oilers' chances to win the Cup in the next three years. (Ekholm is +72 in 100 games with Edmonton, which is crazy.) However, he's 34, plays big minutes, and plays tough minutes (also has to shelter Bouchard a bit). If he suddenly goes down to injury or ages out of his prime form, the Oilers are in big, big trouble in the short-term. So far, so good, but how long can he keep it up...?
2) Partner for Nurse. For all the (mostly deserved) crap Nurse takes (mostly to do with his contract more than his play), he still was a solid +71 with 114 scoring points in the '21, '22, and '23 seasons combined. It's quite likely he'll be better next season than last season, which was his worst by far in quite some time. That being said / hoped, the key is to find a D-partner who can play with Nurse and maximize his strengths, while mitigating his weaknesses. Broberg appeared to be this guy (at least in a very short sample), and now he's gone. So, the Oilers desperately need a solid Dman who will slot in with Nurse and play that stabilizing role. Who will it be?