Considering we don't know the exact specifics of the benefits/limitations that will be put in place with a job stone equip, I don't think any member of the public could give an informed opinion on whether or not classes = jobs. There is no 100% confirmation on if jobs will be restricted to purely their base class' abilities or perhaps 5, instead of 10, cross class abilities.

If this is the case then I believe classes would be incredibly redundant, but if jobs are limited to only their class' abilities then there could still be select circumstances where being a class would make you better suited than the job.

Then there is the possibility that you can use abilities from one other class, selected by SE, that is most likely required to unlock the job. The example Yoshida gave was to unlock PLD, you would need GLD 30 and MRD 15. That would mean you could use a few abilities from MRD on PLD. This could make it harder to simply eliminate classes because multiple are already tied into each job.

Anyways, before I get off topic, my point is that until we know how the class to job relationship works (in the hands-on, practical sense) we don't know if classes should stay or go.