Competitive
Well, just look at the competitive scene in TrackMania. It's a game with (probably) the smallest community and is still active in competitive (ESWC, ESL, GA, etc.). It's probably the best racing game you can play competitivly. It's completely skill-based, without ranks/items/etc., which makes it unique. It's the perfect competitive racing game out there. Just see the fact, it's still there in those tournaments, although its community is probably the smallest.
But there are a lot disadvanteges of this small community in competitive scene. Let's imagine, you're founding a completely new clan. Which players do you want to ask to join ... ? There are always the same "professional" players. You can't ask "nonames", as there just aren't many new players, which are good enough. But what's the reason for this?
Community
The community is probably the best community by all video games out there. It's small, it's nice and most of the players are helpful. It has advantes and disadvantages. Advantage is that you have the contact, even to the professional players. You can just write them, or really play with them. They aren't "gaming heroes, you won't see ever online".
Disadvantages... well, TrackMania isn't getting the attention, it deserves. If the community would be bigger, the attention would be more. Also, I'm just in fear that TM will disappear from big tournaments soon, as the community is too small (-> not enough viewers, e.g. -> not enough attention -> not enough money incoming).
Also, the community puts much effort on the game. E.g. just see the TM edits on Youtube, TmTube, etc. They're awesome, creative and there's a huge amount of work behind them. But they're only getting (on Youtube) 1-2k views, if you're lucky. Though, this community is the most active ever, and the community with the most effort in a game, ever.
So what can you do for keeping TM alive?
No idea, basically. Just keep the community up. It's getting less, but there ARE possibilities to keep it alive. I don't want to see this game dying in 1-2 years. But what can help to keep the community growing? I don't know, do you guys have some suggestions? Maybe referring the game to friends, sharing its videos, telling the people how awesome this game is. No idea.

Just some thoughts of me. I <3 this game and I <3 this community!
Regards,
FD"Crunch