I've been a TB Lightning fan since 1992 and their fan base has been growing since they won the cup in 2004--to the point were every game has been a sellout for the last 3 years or so. The downside is ticket prices have skyrocketed for those of us who aren't season ticket holders due to resellers.
I've said for years that there are only 8-9 solid NHL markets in North America -- and by this I mean a metro area where 15,000+ fans will show up even if it is late in the season and the team is out of contention. These are the Original Six (Montreal, Toronto, Boston, New York, Detroit and Chicago) plus Philadelphia and Edmonton ... and maybe Buffalo, too.
Winnipeg might be on the cusp of this status right now.
All the other NHL teams seem to be in marginal markets where fans will come out and support the team when it is playing well, but they vanish when times aren't so good.
To show you how quickly fortunes change for these marginal teams, here's a link to an article that was published just over a year ago, naming five NHL teams that were candidates for relocation:
Two of the five (Florida and Carolina) are facing each other in the Eastern Conference Finals this season.