4th Range DPS idea after endwalker

[Seraphor]

I still think time mage could be a really good fit for a DoT-based magic DPS.

I think Time Mage has more going for it as a healer than a DPS. Traditionally Time Mage has very little in it's spellset that actually deals damage, besides Gravity and sometimes Meteor. Whereas a Regen based healer that also has a DoT and Gravity would fit the bill perfectly, and that's exactly what AST is.

Basically this.

Theres too much of the Time Mage on Astrologian to even think on adding the Time Mage as a separate job. Heck in game is even mentioned that Geomancer is very similar to Astro as well making the possible adition of Geomancer as well kinda iffy

Geomancer has a bit more wiggle room though, as there are two schools, Yanxian and Hingan.

Hingan is the one that is likened to Astromancy, which features in the AST questline. (it's actually more like Astromancy with a focus on the star below, or Conjury carried out like an Astrologian, half of each really)
Yanxian is the one shown in Swallow's Compass, very different, and is much more like an offensive conjurer. That could potentially work as a magical DPS class.
Neither would work as another healer though, with Yanxian being too similar to Conjurer and Hingan being too similar to both Conjurer and AST.

I would love a Yanxian Geomancer magical DPS. With a giant bell for a weapon, oriental robes, and that giant round hat. Wind and Water based spells, lots of AoE and ground effects, and a channelled turret burst phase.

[Garnix]

Right, and DRK had a lot going for it being a DPS but it ended as a Tank. It doesn't mean anything really. Until they release Time Mage nothing is set in stone one way or the other. Even if they say they will not make it, they can still make it happen.
+ Gaia uses Time magic offensively.
AST indeed uses some time magic in its kit. But nothing like what Gaia does.
Time Mage was usually a support job but it doesn't mean it would be one in XIV.