The real test for Holland is off-ice more than on-ice (not an Edmonton joke).
Mike Gillis would probably get punched in the face by a media member if he tried to fire Keith Gretzky, let alone Wayne. Holland is a guy who can step in and actually clean house without the Jim Matheson/Steve Simmons types of the media getting obscenely butthurt. "Future HHOFer, needs to bring in his own guys, clean house, time for a change, etc."
If he does that (and by that - I mean turfs Lowe, MacTavish, Howson, W. Gretzky, K. Gretzky and anyone else not named Joey Moss or Bob Nicholson), then leverages his massive network in the league to attract a smart outsider... they have a shot at turning things around without it resulting in McDavid demanding a trade.
FWIW Yzerman originally mentored under Holland. Obviously a smart hockey mind, and the Detroit connection is what made him go to that organization... but Holland is also the guy that found Hakan Andersson, Jim Nill was the best assistant GM in the league for years, etc. I wanted Holland here because he clearly has the ability to find talented people and put them in key roles around him. Whether he does that in Edmonton or even has the ability to do so in Edmonton is the question, but it sounds like he was given the authority to do whatever he wants. It'll be interesting to see what he does.