Context: docker people have already announced an intention to work to unlink themselves from aufs dependency.
Alternatives/Reality-check: LVM2 can provide snapshots at the block layer: either through the normal approach with a single depth limit (though you can un-snapshot a snapshot through a process known as a merge, and then snapshot again as required), or through the new/experimental thin provisioning driver to get arbitrary depth (but 16GB max volume size). In both cases it's filesystem neutral, and the first approach is very widely deployed which means no roll-thy-own-kernel requirement. zfs and btrfs also provide snapshots, but are historically respectively poorly supported/slow (userspace driver or build your own kernel for zfs) and unfinished/in development (btrfs). Linux also supports the snapshot-capable filesystems fossil (from plan9), gpfs (from IBM), nilfs (from NTT). A related set of options are cluster filesystems with built-in replication, see https://en.wikipedia.org/wiki/Clustered_file_system#Distribu... Overall, the architectural perspective on various storage design options can be hard to grasp without digging, and higher-layer solutions such as NoSQL distributed datastore applications remain strong options in many cases.
Trend/future?: Containers in general are moving towards formalizing the "here's what I need: x-depth snapshots with y-availability and z-redundancy" environment requirements specifications for software. In the nearish future I predict that we'll see this in terms of all types of resources (network access at layers 2 and 3, CPU, memory, disk IO, disk space, etc.) for complex, multi-component software systems as CI/CD processes mature and container-friendly software packaging becomes normalized (we're already much of the way there for single hosts - eg. with Linux cgroups). Infrastructure will become 'smarter', and the historical disconnect between network gear and computing hosts will begin to break down. Systems and network administration will tend to merge, and the skillsets will become rarer as a result of automation.