Yoshida have said that the sam will be a dps.

about the roster, the game only count the jobs like this:
- tank (drk/war/pld)
- healer (whm/ast/sch)
- melee dps (mnk/nin/drg)
- ranged dps (smn/blm/mch/brd)

it's the player that make the difference between physical ranged and magical ranged, what is important is the position while the fight, not how you deal damage...

another point, we will not have 3 jobs release at the same time, yoshida was clear after the release of HW. it way too much work in terms of balance and such to add soo many jobs (especially if you count that a few month before they had added the nin)

finally, add another tank right now is pointless, since they already have some trouble to balance the three we already have. plus what sort of tank will be the sam?
- offensive one? we do have the war
- one based on parry? war and drk are doing the same
- one based mainly on physical damage? war one more time
- one using a 2hand weapon? war another time...

too many point are too similar with the other jobs already present... without forget that we already have 1h and 2h sword class as tank...