[kaisdavisOR]

> Is a strong, unified online presence a requirement for freelance success?

No. Not in the least. I think a strong sense of marketing yourself is important, and that often ties into developing a strong online presence, but not a unified online presence.

> they have a professional identity that they use across communities, a blog full of relevant professional content, and an attitude towards community participation online pretty much opposite of my own.

That's only one way to do it. There are tons of successful freelancers / contractors that you haven't heard of (not because they aren't successful), but because they're working on developing their skills and getting work, not developing an online presence.

When you want to take the jump towards full time freelance work, I recommend Ramit Sethi's writings on earning more money (http://www.iwillteachyoutoberich.com/) or the earn1k program (http://www.earn1k.com).

IMO, you don't need to wait until you lose your job to start developing an online presence or to start freelancing.