Except for use by those who either want to develop a distribution, build software, or manually configure their distribution beyond what's worthwhile in most other distributions?
Sounds like more of the same to me. Anywhere that I see Ubuntu cropping up, Debian wasn't there to begin with.
I have witnessed Ubuntu replace most of the SuSE installations I was aware of. That's a big win for Debian on the desktop market.
And I've yet to see anybody try to use Ubuntu as a server. Really, I don't get what they're going for with that "server" branch. I guess they want to make it just like using Ubuntu... only not? Kinda sounds like Debian making a desktop fork to me.
Maybe I'm just weird. See, I'm not on the consumer end. I tend to witness a lot of cooperation when browsing around for software. Some of the most productive users of Debian seem to be the developers of other distributions. So long as Debian remains a valuable asset to them, I don't think it's going to vanish anytime soon.