For a garlemald expansion: A Gunblade Job, and Chemist. I say chemist for healer, because if Garleans can't use magic, it'd fit in well. It's also one of the most unique healers in the series, and could have a distinct identity. For a Thavnair expansion I would like Blue Mage, Geomancer, and Dancer. These three could very easily fit with what we know about Thavnair. As for a Sharlayan expansion, I would suggest Oracle, or Mystic Knight, but, Oracle could be tricky. Though to be honest I would also like to see something 100% original and new for the Final Fantasy series in addition to these.