Eventually, when Dancer is added in whatever expansion (clearly not Stormblood) I'm sure it will be a Job only like the other new Jobs. As they've said OVER and OVER they won't make branching class/jobs as they did with ACN/SMN/SCH previously.

And no it doesn't make any more sense to come from rogue/ninja than it does pugilist/monk. Which either way, it's not coming from either it will be a stand alone Job with cross class skills as MCH, DRK & AST are. Why would this suddenly change when they've made it clear it is the model they will be using for new Jobs?