I notice that the latest wikipedia home page does inclusions by using the
{{msg:...} "transclusion" variable.
It seems to me that inclusions like this should come from the
$wgMetaNamespace or other namespace, not the MediaWiki namespace. The
MediaWiki namespace is really for running the software, and should not
really contain specific user modifyable site data.
Perhaps we need a new set of variables for these operations.
How about:
{{incl:article}} # include from the default namespace
{{incl:namespace:article}} # include an article from 'namespace'.
{{incl:language:namespace:article}}
{{inclnw: ...} } # use the nowiki tag
{{repl: ...}} # new version of {{subst:}}
This provide a more general mechanism without making obsolete the old one
and providing a migration path for the type of include used by Main_page.
It also uses the same naming convention as the [[...]] markup.
Nick Pisarro