Today, Kaldari wanted to have translate enabled on foundationwiki so that Special:MyLanguage was available, but that would fall afoul of bug:44871 [1]. This is not a unique request, fundraising also has some use for MyLanguage features on wikis that don't have (and wont have) translate.
Are there any concerns with separating out that special page into it's own extension? The one that immediately jumps to mind is how the i18n team bundles translate.
[1] https://bugzilla.wikimedia.org/show_bug.cgi?id=44871
~Matt Walker Wikimedia Foundation Fundraising Technology Team