While it's true that Klefbom is underrated WHEN HEALTHY, he was really inconsistent last season probably due to playing injured AGAIN so while he did eat up a lot of minutes (boosted by playing a ton of PP minutes), he struggled handling them especially later in the season so I'm not sure if they're losing that much with the version of Klefbom we saw last year.
Also, Nurse and Bear were the top pairing at even strength so I don't think their role will change that much.
Klefbom is a loss for sure but I don't think it'll be as big a loss as some seem to think it'll be and the Oilers puck moving improved drastically with him out and Barrie in.