Given that Dundon signs off on player decisions and Tulsky was already involved in the player management side of things (contracts, who to get, cap stuff, etc.), this shouldn't matter too much. However, Don Waddell has that personal experience talking with every other GM in the league that probably helps when it's time to talk trade. We will lose that experience.
From Waddell's perspective, I assume there are multiple reasons for wanting to do this now, especially if he is going to end up some other team's GM
1) Another team is going to pay him more money (almost certainly)
2) He can focus on being a GM and not have to worry about PNC arena renovations and the massive work that is coming with rebuilding the area around the arena.
3) He probably will have much more autonomy as GM somewhere else.
Less work more pay? Who doesn't want to sign up for that?
I definitely wish him well wherever he ends up.