There are plans to change the default skin to 'vector'. There have been bugs in the vector skin which have broken the Wikisource extensions, but it looks like most have been fixed.
One remaining problem is that the vector skin hides links to other languages. A bug was raised to rectify this, but the fix has been rejected.
https://bugzilla.wikimedia.org/show_bug.cgi?id=23497#c7
On Wikisource, the interwikis are a _critical_ part of the user interface; a translation should _always_ show links to the editions published in other languages, especially the original language(s).
These links will become hidden in the new skin. e.g.
http://en.wikisource.org/wiki/Metaphysics?useskin=vector
Compare with all other skins
http://en.wikisource.org/wiki/Metaphysics?useskin=standard http://en.wikisource.org/wiki/Metaphysics?useskin=monobook http://en.wikisource.org/wiki/Metaphysics?useskin=modern http://en.wikisource.org/wiki/Metaphysics?useskin=simple http://en.wikisource.org/wiki/Metaphysics?useskin=nostalgia http://en.wikisource.org/wiki/Metaphysics?useskin=cologneblue http://en.wikisource.org/wiki/Metaphysics?useskin=chick
If the interwikis are not displayed in the vector skin, either Wikisource cant use the vector skin, or Wikisource will need to move these links into the content of the pages. I've started a discussion about this on the multilingual wikisource scriptorium
http://wikisource.org/wiki/Wikisource:Scriptorium#Vector_skin_and_interwikis
and notified English Wikisource
http://en.wikisource.org/wiki/Wikisource:Scriptorium#Vector_skin_and_interwi...
-- John Vandenberg