config(5) is made of definitions and selections. Selections are basically written in user's config (GENERIC, etc.); commen ones may be put in sys/conf/std or sys/arch/*/conf/std.*.
To follow that naming convention, how about: sys/conf/all.filesystems sys/conf/all.usb ? Users have to filter unwanted ones by the "no ..." syntax. If that will not work, config(1) needs to be fixed. :)
