I believe Yoshi has stated that he plans to add a 'Hybrid' role. Which I assume will mostly end up being hybrids of DPS and 'support' because support abilities (like what a bard has) are useful but it's very difficult in the current game to build a full class out of them. Support sort of sneaks into the game a kind of 'half-role'.

I don't see how anyone will want any other combination of hybrid in a group when a job dedicated to tanking/healing/dps is bound to do it better. I'd like to be wrong though.