I love Prognostication and Speculation so here are my thoughts...

...perhaps the "new jobs" are associated with the Grand Companies and unlocked thru Grand Company Quests...

...perhaps your job choice will also determine the Company you choose, ie. Marksmen only work for Limsa Company...

...perhaps you need the new jobs to do the Company Missions (and will probably want them to beat the Dungeons)...

...perhaps it is all a big new time-sink to keep us busy on R1 jobs while they continue to work.