Wouldn't be surprised if they did a proper Magitek Knight but actually called it "Blue Mage" as the power drawn from the source is ceruleum which is an energy source, but also it's blue like the dye. The magic isn't actually "proper magic", but attacks using artificial magic drawn or based on enemy design in the next expansion. There has been hints that stuff has been in the lore already, as a "Mage Tank" at least the breadcrumbs of it are workable.

I know it's a stretch as a concept but

1. gives a job the community wants,
2. fits into the marketing hype,
3. sits as a good reflection of both the established and new lore of the upcoming expansion
4. leaves a lot of variety for both abilities and may-be weapon design.
5. It would fit Garlemald, particularly as a technology focus but also as a reason to help the player characters etc if jobs are indeed to physical locations as the other ones are.

Then again, Rune Fencer or some other tank could fit this either, but who knows.