People seem to be forgetting that Garuda and Titan are in fact just glamours of Emerald Carbuncle and Topaz Carbuncle. This means the bulk of the coding for the glamour system is already implemented, as SE will clearly utilize the same code to implement all other glamours. The only thing they need to work on is a UI for the glamours we unlock and the models, animations, VFX, and sound. All of which are very easy things to develop, especially the Egi visuals (based off their current design). Unless SE are planning a complete visual overhaul of the Egi.