It's the trick for any property to be a commercial success: You have to find an audience for it. In traditional publishing, the publisher does (or did) a lot of that work for the author. Hollywood films and network TV have huge production companies and networks and millions of dollars working for them. In the digital age, things are a bit harder. Ian David Moss talks about the Marketing Arms Race, and Simon Pulman expanded that thinking with Smart Fan Engagement when it comes to transmedia. The thought is that in this digital domain, without the content gatekeepers of the editor or producer, there's an explosion of content. With all that content, potential audience members can only devote time to so many products. And what marketers and transmedia producers want from their audience is as much of that time as possible -- we want people to become truly involved, immersed, and invested (the three I's?) in the content.
And people just don't have that much time. Audiences become fractured. And we all compete for the same people.
Simon Pulman has some good points about finding and keeping that audience for transmedia. And it's something that a lot of artists are trying to wrap their heads around with the internet and social media. Part of finding that audience is providing a lot of your content for free -- then you have a base to which you can try to sell from there. (Using social media can connect you to an audience -- today's Digital Book World Roundtable discussed some of those issues: when someone "Likes" a property on Facebook, there's a deeper involvement than if someone Tweets a link to it -- but Twitter allows a much broader diffusion of information.)
Perhaps what we have to start really looking at is targeting smaller audiences. If we understand that people can't commit large amounts of time to every project out there, and more and more projects are being made, then we can understand that we're each not going to have a big slice of that pie. And if we know that, we can plan content (and budget!) accordingly.
Alternately, make it easy for people to have only a passing involvement in the project for a larger potential audience -- and then those who want to really be invested have somewhere deeper they can go as well.
If the project is grown from a base medium -- a TV show or book -- then you have a ready-made audience there. But it's still about using all media to find an audience, and having compelling enough content to draw in at least a few of them to a deeper level of involvement. And those are your true gold mine -- they'll be the ones investing their time, passion, and potentially money in what you've created.