There's plenty of free software stuff to work on with Linux that a ton of people use and enjoy. And then there's stuff that, to me at least, seems like a "suicide mission":
Jolla looks to me better than Openmoko when it comes to adoption chances. And they are doing things right, basing their work on the common middleware (Mer + Nemo). PlasmaActive also uses Mer. They aren't suicide mission, they are a startup with planned strategy and aim to be profitable. Let's see how they fare.
I wish them the best of luck; I was just explaining why as a developer, I'm a bit leery of a new platform like this. I feel for them, as I know it's a very tough spot to be in.
It's tough on one hand, and it's a wild frontier waiting for more pioneers on the other hand, since there is lack of innovation (Android and iOS are pretty much stalled when it comes to introducing new ideas). So newcomers have good chances of providing interesting alternatives. I'd worry more about the sickening patents situation, than about lack of interest in new platforms.
But surely they'll need to attract developers more, since many aren't familiar with Sailfish. There was a recent post about from Mer folks:
http://en.wikipedia.org/wiki/Openmoko
Bright people, good work, and so on, but it's sad to see something you do go nowhere.