Well you CAN do anything you want. HOWEVER I would say that since Miqo'te canonically hate the cold and due to Ishgard being a 70/30 Elezen/Hyur split by the look of Coerthas' population, that a Miqo'te living in Ishgard, let alone being an Astrologian, would be exceedingly rare.
However with Heavensward coming up, who knows?
However with Heavensward coming up, who knows?