I think the issue with thinking that WHM's transition into Light aspected skills leading to something like Geomancer in the future is that for levels 1-70 WHM still uses Stone/Aero and 1-30 as Conjurer is literally all about Elementals.

Unless they retcon Conjurer and replace Stone 1-(Whatever number we're currently at... 5? 6? 20? Heck if I can keep track) and Aero 1-3 with more Light aspected skills, I'm not so convinced that they'd be bringing in a new job that focuses on using Stone, Air or Water elements.

In addition, they would have to adjust Red Mage too, as they also use Veraero and Verstone (Also, are getting that new skill, Veraero which isn't Veraero, but is Veraero. I honestly have no idea what was going through their head when they made the 2 new RDM skills literally have the same name as 2 of their existing skills >.>) and since they're based off of Black and White Magic not Black Magic and Geomancy, it would be odd if WHM had Stone/Aero retconned from them but RDM would still use them as White Magic skills.

I think maybe at this point the major reasoning for the transition away from Stone/Aero is partially due to where the expansion takes place (A world full of Light) and partially due to possibly running out of new ways to think about animating Stone and Aero skills >.>

My thoughts on the subject of WHM's skill types?

I don't know... Personally, I'd love to see Conjurer get more love in terms of having more elements to use. Water skills, Fire skills, Lightning skills, Ice skills... You know, all the naturally occuring elements that they should be able to wield. But at the same time, given that White Magic is heavily based around Light aspected skills it'd also be neat to have more development there, especially if it means learning more about the Amdapori...

In an ideal world... I'd love to see Conjurer be a separate job to White Mage... But alas, t'was not meant to be...