I am curious to know how Ubuntu will handle later updates if I install other *-desktop metapackages such as kubuntu-desktop, lubuntu-desktop etc on a default Ubuntu installation.
As dist-upgrade command upgrade the distribution, what will be my final distribution. This question is important because dist-upgrade can install and remove packages to satisfy dependencies, so it may remove some packages say for example, dependency of ubuntu-desktop to satisfy dependency of kubuntu-desktop
A 'metapackage' is no more than a simple way to install a bunch of packages at once. It will be no different from how it would deal with an individual package. apt-get upgrade will update each individual package and its dependencies. Referencing an older question it will install any necessary dependancies, even once you explicitly removed, and remove any obsolete files.
It however has nothing to do with upgrading your release. You will be on the same version of ubuntu (say dist-upgrade on 12.04 will give you 12.04.. with newer packages).
For getting a new version of ubuntu on release the command will bedo-release-upgrade-d
We can handle one or two desktop environment with a single system. Your final distro will be mixed of all.
You will get to keep all the desktop environments you install. They aren't different distributions, really, just like Ubuntu Server and Desktop aren't - you can install ubuntu-desktop on a server and get the GUI. They are just different package sets from the Ubuntu archive.
You will be able to boot to any of them from the login screen (lightdm, if that's what you started with), and all/most the apps can be run from any of them.
