DK1 seems like it is almost still working. I just tried it and it shows up in the settings as connected and working, but games won't launch because there is no tracker. And the display doesn't turn on so it won't show home screen either. When I get a chance, I'm going to try to build Unity app with new 1.3SDK and launch outside of store to see if that works or not. Older 0.8-built apps no longer work with new runtime loaded. I'm not sure why I care so much, but I want to see the DK1 still keep working even though I have DK2, and CV1 and Vive on the way.
I tried it with Elite Dangerous (Has been updated to use 1.3). The desktop screen shows that the tracking is working from the DK1, but the rifts' display doesn't come on.