The problem is not a lack of interest, but the lack of cheap, programmable hardware for teenagers to cut their teeth on. For typical youngsters, computers have become too complicated, too difficult to open (laptops especially) and alter their settings, and way too expensive to tinker with and risk voiding their warranty by frying their innards.
I don't see the connection between learning to code and having super-cheap hardware. Back when I was a kid learning to program I actually had to pay real money for a compiler. (Anyone else remember Borland Turbo C++?) Now you're tripping over free languages and environments to use, including many that run entirely through your browser so there's zero risk to your machine.
Honestly how many teens are going to go full-David Lightman and be doing serious enough hacking that their hardware is at risk? Is the goal to make sure teens have the opportunity to start learning to code before college, or to give them hardware to tinker with? Those are both fine goals. Being a software guy I'd put more weight on the former, but the important thing is that the way to accomplish either are completely different.
For starters, [your correspondant] plans to turn his existing Raspberry Pi into a media centre. By all accounts, Raspbmc—a Linux-based operating system derived from the XBox game-player’s media centre—is a pretty powerful media player. The first task, then, is to rig the Raspberry Pi up so it can pluck video off the internet, via a nearby WiFi router, and stream it direct to a TV in the living room. Finding out not whether, but just how well, this minimalist little computer manages such a feat will be all part of the fun.
I did this exact project about a month ago, and couldn't be more pleased with either the results or the fun of getting it to work. I still have to tinker with some things: the Vimeo plugin won't log into my account, and I need to build a case. Other than that, I wish I had done this a long time ago.