Even if all the hobby supplies vanished, I'll still find a way to fly. I'll still have my radio gear and servos. As long as I have that I can make do. Many years back I heard of a guy that built a plane using door skins and fabric from a cloth store. No balsa. Flew it with a conversion engine. I know a racer that makes composite fuse formers for his racing planes out of 1/4" foam with glass on both sides. He says it provides plenty of strength for the racing environment and cuts like balsa. I'll find a way.
Edwin