How much Dev work would it be..

[RitsukoSonoda]

Unlikely. SE decided they didn't like it on WHM (and THM) and it's effectively gone now - unglamorable, and no new content for 4+ years. Even though there's been some jobs that could reasonably have an off hand, like red mage.

I think it's staying for PLD only.

Part of that decision may have also been to possibly open the door for 1 handed wand/rod to be a caster weapon for a later job. Previously WHM/BLM were a sort of oddball in jobs where they had both 1hand and 2 hand options.