ePUB and ZIM are likely to return. The new architecture makes it quite easy to add "html-like" backends, and both epub and zim are similar in that sense. I hacked on an initial zim backend at https://github.com/cscott/mw-ocg-zimwriter during Wikimania with Emmanuel. But I am rather overcommitted at WMF (in addition to my "real job" at the Parsoid project, where I'm in theory working on language converter issues this quarter, I'm also creating/maintaining the OCG service and lending some real-time collaboration help to the Visual Editor team). Hence Erik's help-wanted. --scott