Based on Andre's comment I have an idea with a
different approach that may
help.
What if MediaWiki would have a special page indicating which linked
images/files on the wiki would have no actual file available locally or on
commons/a shared filestore? That way wiki administrators could more easily
get insight in file/image red links and Commons administrators would have to
delink 'off site' a lot less, since local wiki administrators would have a
more comprehensive insight in their red links related to images/files;
together with the Commons Ticker, I may even be no longer required to delink
off-site if the admin 'does not feel like doing it.'
I have searched
http://bugzilla.wikimedia.org and haven't been able to find
a feature request for such a feature at the moment. As far as I know this
feature is currently not available, although functionality may be closely
related to that of Special:Wantedpages. If this approach would serve both
commons admins and local wiki admins, I think it would be worth trying to
get this feature built.