to weigh in a bit here... I don't have a Scrambler (yet) but probably will soon, but i'm still researching... anyways, the day Yamaha XSR700 was announced, it peaked my interest. And I thought, I bet this will be a popular bike that people will want to talk about, so I registered xsr700forum.com
and set up a message board there really quickly. I'm a web designer, so this is easy enough for me. Not a lot of people have found my site or registered yet, which makes sense because the bike isn't even available yet, but I figure it may happen in time.
Well, a few other people had the same idea, so now only a week after the bike was announced there are at least 4 message boards for the xsr700, all with very few posts/membership. One will probably become the most popular, and the rest will die off a bit.
TL/DR: Setting up a forum is easy enough, so many people may do it.