If you mean it as a way to backup your system, sure, why not. There have been some ideas on the forum about creating a tar "install package" that you just untar to have a working Arch, but I've never seen a working example.
You can move your packages to the new computer in order to avoid redownloading them. but backing them up is generally not necessary.
Hmm I think that would be easy to do since technically Arch ISOs are just snapshots at that current point in time. Which would mean that if I installed Arch and directly after an install I run the commands to create a tarball, that tarball would be the same as the Arch ISO (with extra configurations specific to the system). If someone wanted to install it, it would be similar as to installing gentoo. 1. Extract that tarball back into the system 2. Reconfigure the core files, add users, etc 3. Install GRUB (or any other bootloader) -- Jonathan Vasquez