Nothing regarding the new classes has been confirmed yet. We know there will be more than one, but that's about it. The Scarlet Witch reference is a very strong hint that Red Mage is on its way, but is in no way an official statement or confirmation.

Outside of that hint towards RDM, and potentially whatever Alisaie's abilities at the end of the last MSQ may have hinted towards (if it actually hinted towards a new job at all), there is absolutely nothing to suggest the identity or number of new jobs we'll be getting in 4.0. Anything you hear beyond that is simply baseless speculation and rumour.