I have just pushed a new version of the TitleValue patch to Gerrit: https://gerrit.wikimedia.org/r/106517.
I have also updated the RDF to reflect the latest changes: https://www.mediawiki.org/wiki/Requests_for_comment/TitleValue.
Please have a look. I have tried to address several issues with the previous proposal, and reduce the complexity of the proposal. I have also tried to adjust the service interfaces to make migration easier.
Any feedback would be very welcome!
-- daniel