Wouldn't it be getting older?
I mean the once-young older members of the fandom are now getting older... And except may be things like brony, deviantart circles and some game fans there aren't as many things that you might find the furry fandom through, right?
Though, I think it'll increase with the world's population. I think if you see any boost in popularity, it's an illusion caused by how some small communities have collapsed and replaced with larger ones, especially in relation to the advent of large scale social networking sites like Facebook and furry-specific sites such as Fur Affinity (before, I'm sure there'd be more furries on other networks like MySpace, virtual worlds, MUCKs/MUDs).
When I found the fandom I cut straight to research.I found the maximum average amount of users of creative/fan furry sites to be currently 200,000 (from a statistic that may include spam / multiple accounts, and it seems the average active poster of such has 20 posts). Those who would have once otherwise once associated with things like funny/cartoon animal, were, game and Disney/etc related fandoms (such as TLK) seem to also consider themselves as furries purely because of how the term has spread, yet there is also a decline with association due to negative furry stereotypes. One thing the internet gives is the illusion that there are more or less than there is, depending where you look. I mean it's like things with corporations, anthropomorphic animals and the likes have been a part of media/culture for millennia and it doesn't really directly relate to promoting the furry fandom or what not (furry fandom is a fandom not a product, to make money with it is best to be an artist who makes commissions, I think).
I mean I joined the furry community at the age of 19 when I registered on here a month or so ago x3
I had not heard it in media, if I did it didn't come to my attention, and I think most people would be like "meh" if they saw something, especially if they had no interest whatsoever. But I learnt about it online and understood it, as being a type of therian, I can associate.
But I do conclude the furry fandom is expanding, not much in relation to the world's population, but the younger age thing is probably just an illusion :3
I also found this link for popular base of artists on FA, which may correlate, too (note quite a lot in the list are mature and even adult-oriented it seems):http://www.popufur.com/