On a site that deals with series and franchises that are constantly being updated, such as Science Fiction and Fantasy, there are a lot of unreleased works for which the title may not be known, but a great deal of information about the work might be. For example, the title of the next Fantastic Beasts film has not yet been revealed, but we know where it will take place. The eighth and ninth Star Wars films are still untitled, but we know which cast members are planned to return. Some unnamed works, such as the latter two (star-wars-8 and star-wars-9), have their own tags.
On the one hand, such provisional tags allow cataloging and following potentially answerable questions about popular works that are currently untitled. On the other hand, many such questions are likely to be future works, and may need to be renamed by moderators when the work acquires a title.
Should we make provisional tags for works that don’t have a title?
franchise/work/author + [sequel]
seems to be how we're doing it now (and I doubt most those questions are being retroactively updated)