Chris - while there are other rim brake manufacturers (Paul, Tektro, etc.) who are still making rim brakes, I think one of the concerns - and it has been batted back and forth on this blog as well as by Grant on his own Blug - is that if rim brakes disappear entirely (which I doubt) and cyclists are forced to use disc brakes, they won't be able to do so without a front fork change. AND, as Grant has pointed out, not all forks are built substantially enough to work safely with disc brakes. One of the issues discussed had to do with which side of the bike's fork the disc caliper is located.
Just this past week a cyclist in my area had a front wheel "fall off" while riding on a path and he sustained serious head, face, and other injuries. I'm waiting to find out the details, but I wouldn't be surprised if the bike had a left-side disc brake mount and he hadn't tightened the QR sufficiently, and it worked its way loose during hard braking.