So, now Monk/Dragoon have to compete with yet another class?

[Atreides]

http://xivdb.com/?search/!patch-Patch2.28

well,judging from 2.28's data mining under the skills section,most likely Rogue/Ninja's main stat will be DEX

I think that would be the new gunner class they work obviously with dex, I highly doubt they add 2 new Dex based classes.
Ninja are close combat and dex states it affects Ranged damage and parry, block rate thats about it.