As I've suggested before, They need to Port / Remake FFXI into the FFXIV engine making Vana'Diel an Expansion Area to XIV where it keeps it's uniqueness and is it's own Area with separate rules for leveling, gear etc, keeping in line with what made FFXI the game it is. This puts all the devs for the game(s) on the same code base as far as why it would be doable / practical from SE's point of View . Start with the main game pre RoZ to start, then proceed through each expansion. Adding some of the modern conveniences like Warp Rings and HP tp's etc.