Shipping libc6:i386 in the amd64 images would be useful

Without /lib/ld-linux.so.2 in the base image, 32-bit executables can't be loaded. There are some hacks to get around that:

1) Mangle ELF headers to point at an ld.so you ship with your snap (no tool support for it and super hacky anyway)
2) Use overlayfs (not ready yet)
3) Use a kernel hook to swap out which ld.so gets run (requires privileges)
4) Prefix your 32-bit command with the full path to an ld.so you ship with your snap (doesn't get inherited by subprocesses)

So none of those are quite ideal. libc6:i386 is about 10M on my system. So it's not tiny. But it's the easiest/best way to allow 32-bit executables in snappy.

It doesn't seem so unreasonable that ISVs would want to throw some old 32-bit executable in a snap.