I have contacted a number of developers inquiring about the status and/or possible release dates for apps for Blackberry 10, and have received responses from almost all. Responses have ranged from no plans to support BB10, to "wait-and-see", to actively working on it.
I've created an open Google Spreadsheet with contact info for most of the developers who are still holding out on BB10 support.
Please go through the list, and fire off an email/tweet to the ones you're interested in. See the link below.
I think that while BBRY is ultimately responsible for the success or failure of their ecosystem, the user base has some role to play as well. If a developer has BBRY dev relations people contacting them to produce an app for their platform, and they aren't getting ANY feedback from their customer base whatsoever that there is actually demand for said app, they're going to push back on BBRY until they learn otherwise.
Alec Saunders isn't exactly Tom Hagen from the Godfather knocking on developer's doors and making them offers they can't refuse here... These devs are ultimately free to do whatever they feel is the best business decision. They aren't throwing resources into WebOS because they don't see enough of their users on that platform, and similarly they don't throw resources into BB10 because they don't see enough of their users on that platform, simple as that.
So if there's an app you really really want to see become available (offically, not sideloaded) then don't start a thread complaining about it. Open up your email inbox, and fire off an email to the developer themselves.
I've had people tell me that is a silly, useless exercise, but I beg to differ. Endomondo is one example where a bombardment of user demand forced them to do a complete 180 and reverse their decision not to support BB10. See the link below for proof.