I don't really see it that way. They are saying they liked the guy so much and thought so highly of his process that they are going to have the guys who worked closely with Ek continue that process. Hiring a new guy from the outside would be throwing everything Ek did out the window and starting over. Who knows how that would go.
Yeah, maybe the key ingredient here is Ek himself and his former assistants won't be able to replicate his success, but I understand what they are trying to do. They're not "not replacing him," they are replacing him with the guy(s) who worked the closest to him and know his methods.
And yeah, saying it will be "better" is probably a little hyperbolic, but I hope it can at least maintain the level of play.