While Docker specifically is bit lackluster, I still feel like the underlying container concept/tech and nix would complement each other nicely. Nix for building the rootfs and lxc (or whatever suitable runtime) to run it.
That's exactly the kind of tool I'd love to see in 2015. Not only but in particular for Haskell development. nix seems to gain traction to set up your dev environment, but it's still pretty clunky to use at this point.