On Monday (2016-09-12), I plan on deploying a change that allows most
users to change the "content model" of a page (the
user right). This functionality has been available to administrators for
a few months now. The permission is similar conceptually to "move", so
it is being granted to all groups that have the "move" permission (and
taken away from those that don't have "move"). Specifics can be seen in
the Gerrit change.
This functionality is mostly technical, and documentation can be found
at <https://www.mediawiki.org/wiki/Help:ChangeContentModel>. Currently,
the main usecase is to allow any user to create a MassMessage target
list, but others are planned in the future.
If you find documentation missing, or want to change your wiki's
configuration, or have questions in general, feel free to respond via
email, or file a task in the MediaWiki-ContentHandler project and CC me.