I will say this first of all, I would like Nashville to keep the Preds but the realist in me says that's a slim chance at best.
I've been to Houston before and I have family there.
The interest in Hockey is quite underground there. Most people are genuinely interested in: NFL Football, College Football, Baseball, Basketball, High-school Football, College Basketball, Rodeos, Soccer, Arena Football, Motor sports, and probably Hockey is at/near the bottom, right with the WNBA.
Granted, the Aeros are an AHL team and it's not expected that they would get that much attention with so many other sports competing. An already competitive NHL team would likely gain a lot of interest in Houston. Could it be as successful as Denver has been with it's relocation? Maybe not, but I think it could develop quite well over, say, 3-5 seasons if the team were competitive.
Unfortunately, the Preds have unloaded some key pieces to their roster and several UFA's are currently uncertainties.
Would KC fare better? Well, there are less sports to compete with but the metro population is less than half of Houston's (probably about 2/5 the size).
I think, however, KC is probably more interested in gaining an NBA team than an NHL team. But, since David Stern isn't vying for expansion, and KC is now apparently 2nd after Oklahoma City (this, of course, assuming that Seattle miraculously isn't relocated there and that Stern actually will expand the NBA to 32 teams) they're probably just desperate to fill with any semi-to-well-drawing tenant.
Is Hamilton a better choice though? Honestly I don't know. I feel that the strength of the Canadian dollar is temporary (2-5 year track) and without that, Hamilton would be hard-pressed to keep a team long-term.