Wordpress is kind of a "one-off" in the same way that Farmville and Minecraft were (i.e. right place, right time -- Newspro and Perl CGI was falling out of fashion, PHP4/MySQL3.23 were common everywhere, shared hosting was easy, and Wordpress came bundled with CPanel IIRC).

A more sustainable business model would be, I think, the safe middle-ground for both the consumer and the developer-- the Atlassian model. Offer an absurdly cheap .jar/.dmg/.exe out of the box which you can run locally for the end-user/small-business (what is it like a dollar a user a year for the self-hosted binaries?) and limit it to 5 or 10 seats. If the acquire-hire-kill by GoogAplTwitSquare happens, you still have a local copy of your data and the ability to migrate off the platform. If >(5||10) employees are using the application as a critical component of your business, making the seat-fee price-jump at that point is worth it (value provided > cost of seats, even at a few hundred dollars a month).