Honestly, I'd rather it didn't, or at least maintain the standard Arch as it is today. I get the appeal of immutable distros/installs, but they are just not for me. They feel like a lot more work, for not much benefit.
Also, given that Fedora atomic distros are the ones people seem to compare against, I don't like that flatpak is effectively required. I like flatpak and what it offers, I don't like that all apps I install must be flatpak, or that I have to go around that default in some way (when I tried one of the atomic spins, I kept running into apps that just didn't distribute as flatpak and it made things more difficult). I suppose this old dog doesn't want to deal with some new trick just to use his system like he always has with a simple pacman -S or apt install.