It might be beyond the scope of Fedora 26, but I'd like to evaluate the liabilities (pros, cons and gotchas) of supporting all possible user defined layouts (within reason) out of the box. That is, ext4, XFS, Btrfs, overlay(fs), dm thin. Surely this is a boolean problem, and the setup just needs to know what's being used, and automagically do the right thing.
The most obvious flaw with this idea, is the move to overlayfs is intended to shed the baggage of docker-storage-setup and LVM thin, but ideally I'd like to see atomic support a few sane (whatever that's defined to be) layouts and automatically use them, so we can better figure out what works well, and what works poorly, for various use cases.
Chris Murphy