Branch Page, and cherry pick changes for final version
use case 1: in bigger wikis one gets easier edit conflicts. it should not be necessary to resolve them immediately but just store a branch and later put this change into the then new main page (transplant it there).
use case 2: somebody introduced something wrong 3 revisions back it would be great to undo exactly this change but keep the later two.
technically spoken this means doing something what you do to source code with darcs/mercurial to wiki pages with "cherry pick" or "transplant".
this could be considered when doing a storage refactoring.