Well if you are talking about the original four teams then id say its relatively popular but the franchises in Phoenix, Tampa, Anaheim more than makes up fo it on the downside. But heres a fact, theres more hockey fans in Mississauga than all those original four team states in the US combined. I was a huge Islanders fan growing up in NY, trust me, no one cares in NY and the only reason it picked up momentum in the city itself was because of Messiers miracle Rangers in 94. But even then, I get the feeling everytime I watched the Rangers at MSG that we are the only fans, its a tight knit group and its pretty limited outside the Garden.
MMA isn't just popular in North America and not really anywhere else... I'm sure a lot of people watch UFC here in the UK, and according to a guy I know who's been training theres more and more new people joining every week. So there is interest and a growing number of people training and fighting. And of course its very popular in Japan too. Its still a niche sport though, and it's yet to establish itself like hockey has and it has a short history. Too early to tell if it will be bigger than boxing in the long run, but it certainly does have the potential.