This sounds very painful... we have quite a shitload of deps to convert afais. Not sure if that will pay off.
What would use multilib xine-lib? xine-lib is for gxine, xine-ui, vdr-xineliboutput and quodlibet Rest are somewhat unimportant, and I don't know of any binary-only packages that would require 32bit xine-lib
At a first glance, opencv & efl are potential future candidates. Also DirectFB if we decide to convert it.
directfb isn't scheduled for conversion anymore, so I personally don't really care about this currently
Dropping 484250 as a blocker since FusionSound is part of DirectFB now.