I'm not sure how much of an uptick in attendance from Central division teams will be seen. It's possible that with more chances for those fans to see their team in town, that they'll just spread out across the extra divisional games. It's probably true it'll come out ahead, but still the argument the NHL made sounded quite like an after the fact justification if you ask me. It's questionable that the team really wanted to move divisions, but rather that the Coyotes are doing it for the best interests of the league. The new owner Meruelo came in after it was determined if I'm remembering correctly, so it was probably easier to get that through before he could object.
I also think the rivalry between the Coyotes and Knights was spurned by this. It's going to go from 2 or 3 home games a season against them to 1 or 2 depending on the season. I know rivalries can develop from playoff matchups, but geography is certainly another natural fit and both teams are probably going to be decent the next few seasons, so that could have worked out nicely. Currently, we have at best a rivalry with the Kings, but they have other closer rivals and we just met once in the playoffs of late and it was a while ago now. Anyway, more so with Las Vegas. They could have hyped up the Duel in the Desert a la the University of Arizona and the teaching school up north. Perhaps something along the lines of Sonoran > Mojave.