You have it right on the money. If people keep coming back because they love to use the site, you should experience continuous growth. They will also be likely to tell other people about it, giving you viral potential.

If you cannot get users to stick, no amount of front page Reddits and newspaper mentions will save you. Even though organic traffic is consistent, even that levels off after a while, is hard to obtain, and is dependent on having a massive number of pages with unique content.

We have started to focus on that, trying to get people more involved and giving them reasons to come back to the site. It is a weakness of ours at this point but something that is solvable.