One thing everyone is forgetting (or maybe didn't know) about the Mac Mini is it's broad versatility. Apple has no other computer that can:
be mounted in a car and be used for GPS, play DVDs, music, games - sure, the iPod can, but not full-featured versions.
be tucked away in a a/v components cabinet and integrated with your home theatre with the finesse the Mini can. iTV is still too immature.
the Mini is a great computer to run x10 systems in a home controlling lights, air, heat, electronic locks, exterior cameras, alarms, irrigation, etc. With remote control, you can monitor the Mini from your office desktop computer or your laptop miles away.
What I am afraid of is, people will realize the potential of the Mini after its demise and it will be too late - just like the Cube and the Mac SE. So, unless Apple is planning a replacement, we need to keep the Mini alive. We also need to bombard Apple with letters urging them to do so with suggestions on what we can do with it!
"It may be small, but give me a chance to show you what I can do with it. It can be huge!"
Congrats on your first post.
I agree with you that the Mac Mini has a lot of versatility, and for low-demand tasks (Front Row console, i.e.) a lot of agility. The Mini, I feel, trumps the

TV in (almost) every way (the Mini can't easily grab media off of other computers via Front Row). Unfortunately, the cool applications you suggested are extremely low on Apple's priority list. Apple certainly did not have them in mind when they designed the Mini, as they are definitely niche markets... something Apple avoids like the plague (which is evidenced by their lack of a mid-range tower).
It's hard to tell how much of a priority the Mini is to Apple without seeing more specific Sales & Margin data.
At the same time, I think Apple is being way too paranoid about having a tidy product line. There are way too many people interested in Macs and there are a lot more roles that their computers need to fill. I see an effective desktop line-up as being as such:
(*optional and probably not appropriate just yet) iMac Mini (users who don't need much power, don't need a honking display, and just want the simplicity of an AIO).
iMac (users who still want the simplicity of an AIO, but with a little more power, and a larger display).
Mac Mini (headless, and comparable, performance-wise, with the iMac Mini/iMac; same as today.)
"xMac" (headless, powered inbetween today's iMac and Mac Pro.
Mac Pro (professional machine)
I really think that Apple could profit pretty well in the Tower business but there is so much hesitation to expand. This isn't the Apple of 1994, with a scattered and confusing product line handful of customers. Macs are in, and more people than ever want to switch. Apple just doesn't always have the right model for them.
-Clive