Thief>Ninja/Dancer Class/Job

[Themis]

The question arises once again: Do we want overlapping designs or not?

We don't have a specific niche to hide THF in (enmity transfer and lolTreasure Hunter), so your options are pretty much limited to standard MMO dagger class (WoW's Rogue class and Rift's Bladedancer soul would be excellent starting points for THF gameplay, IMO). Ninja, meanwhile, would have to be designed as DPS as well, and that's not even taking limits placed by their aesthetic. My gut tells me NIN is going to sprout from PGL; no way in hell they have PGL/MNK the Fuuma set and not keep that in mind.

Keep in mind that Yoshida has already told of plans to introduce classes/jobs which serve in multiple roles as hybrid jobs. It doesn't have to be the case that a Job is either a healer, tank or DPS, but can fulfil more than 1 role depending on the situation. With that in mind, it's quite possible that future Jobs will overlap with current ones (and new ones) in their ability set/roles.

Here's the quote from the 2.1 patch interview (emphasis mine):

Will it be divided up by light party/full party content?

Yoshida: Apart from the Crystal Tower which is alliance content, we plan for endgame content to be focused on a unit of eight players. For example, gathering Allagan Tomestones is good for a light party, but I feel like eight players is the smallest unit that should take on strong bosses.

Any reason in particular that you feel that way?

Yoshida: Yes, we want to make sure that there is space in the party for at least two people of each role. 4-6 players is a number which has been used frequently in recent MMOs, but I stuck with the figure of eight people since back in the design stage for the aforementioned reasons. You can have two each of healer and tank and four DPS in the present situation. Once we add the hybrid role (which serves multiple roles), you'll be able to have two players from each role, for a total of 8 people.

Source

Perhaps that will give some means to further the discussion here.