Personally I think flatpak is going to be the future for application containers:
http://flatpak.org/
But that is probably because I am a Red Hat fan rather than Canonical
It does not have to be a 'proper container', it can be a library bundling technology. It's highly integrated with Gnome, which is now the default for Ubuntu as well as Fedora.
Having an official Reaper repo that has RPM and .DEB would probably be the ultimate.