I mean I definitely think it could fit in another system. But as is Casters are a ranged category. At best you'd maybe get something like a cross between a Black Mage and Red Mage to make it work? But even that seems kind of clunky. That's really the issue when people try and propose something different. If it's melee or ranged depends on the role, and the most you'll get is something like Red Mage (or in reverse though I don't think any melee DPS quite does that currently), which really isn't a in your face Golbez style mage. It would be fun certainly, and I wish we had a melee caster DPS role, but it is what it is. The imbalance of physical and magical kind of bugs me.