The Canucks defense has been bad for as long as Demko has been here so he gets the benefit of the doubt because of all the 5 alarm saves he needs to make constantly. Few teams, if any, allowed so many side to side chances as the Canuck defense did. So you almost give him more props for his good saves because his teammates are out there acting like clowns.
If (and that's a big if), the defense becomes better and more structured, Demko isn't going to be getting the benefit of the doubt as much. His play is going to be under a lot more scrutiny if a goal gets scored if the d-men and team in general is more structurally sound.
Much like how Luongo was a better goalie when facing 35+ shots a game, you have to wonder if Demko can adjust his game and still play lights out when only facing 20 to 25 shots a game (assuming the team can actually play like that).