Columbus or Tampa aren't going anywhere, they both sell out practically all their games, and have great lease arrangements with their respective arenas. In Tampa's case, the owner of the team also owns the St. Pete Times Forum, do you really think he would move to a new area that he doesn't own the arena? Not likely.
Nashville also seems on solid ground. They have a good solid base of fans, but the problem in Nashville is the corporate support that most teams feed off. While the music industry is huge in Nashville, it is still a relatively small city, albeit a beautiful city. No, I wouldn't bet on Nashville leaving anytime soon.
Pittsburgh is definitely a team that could move, and I also hope they stay put. But the situation is what it is. Lemieux realizes that the future of the team requires a better arena with more money making streams. Without that happening, they are as good as gone. That's just the bottom line, and from an owners standpoint, it isn't greed, it's common sense!
Other teams that IMO could be in trouble are NY Islanders, Edmonton and even St. Louis. I think we saw a great wave of expansion in the 1990's, but now with the new economics of the game, we might see a newer wave of team transfers. Only time will tell.