I can understand people not seeing the advantage of discs but fearing them? That I don't get. What is it that you fear?
I guess I can see some trepidation in having to use something that is new to you. I was concerned when I got my first motorcycle with fuel injection and electronic ignition that I wouldn't be able to maintain it myself but after getting a few new tools and reading a bit, I found that it was just as easy to maintain and a whole lot more reliable.
In any case, there are millions of bikes on the roads with rim brakes and I suspect parts will be available for many years to come. If you're really concerned, pick up an extra set and store them; maybe even a newish frameset from someone that has upgraded to discs.