I would be worried because Plushenko has not yet proven himself as a technical coach. He very well could be/become a great technical coach, but so far we don't have any proof of that. And yes, he could do quads, but the ability to do a jump does not always correlate with the ability to teach them. Sasha needs a good technical coach to help with the consistency of her quads and 3A. I'm sure he'll give her more attention than he has in the past to other skaters (at least he will if he really wants this coaching team to succeed, as this is his big shot). And yes Volkov (her first coach) will be there, but he taught her triples, not quads. No one else in Plushenko's team has ever successfully taught a lady a quad. I can't even think of a male skater they've taught a quad, but I'm not sure on that one.
The Eteri coaching team is where she got the quads, and I was just saying that it gives me peace of mind to know that someone who can successfully teach that technique will be there with her. Overall I'm not saying that it wouldn't work if not for Rozanov, maybe it would! But Rozanov being there, in my opinion, makes it a lot more likely that it will work out. Rozanov is the only one of them who has seen the process of Sasha (and many other girls) learning quads, warming them up in competition, and has even held the harness for her. And as I understand it, he had a big part in training/maintaining the quads of the youngsters like Akatieva and Zhilina - proof that he knows how to teach ladies quads/quads in general! Of course its not a bad thing to have Sasha's first coach there, I just wouldn't count on that to help make her quads more consistent when she never got quads or a 3A under him in the first place.