There's actually also a fmt=jsonld option for /ws/2 that works where it's been implemented (which is not everywhere). It's a bit weird, since it doesn't usually have the ability to include as much information, and since it changes depending on inc parameters (though the serialization doesn't care about them – it just includes data if it's there, and doesn't if it's not).
In-page markup is probably the intended method of consumption for now, anyway, and the new format for the WS should be relied on even less than the main JSON webservice (and probably should remain undocumented outside of this ticket).
The #MetaBrainz Meeting of 2016-05-30 decided to keep the ticket open: http://chatlogs.metabrainz.org/brainzbot/metabrainz/msg/3609785/