One thing i have thought about with doing free world transfers is that I think the world transfer system is set up for both FF11 and FF14 because both games are run through the square enix account management.

One idea that had gotten formed on another thread I had started was to do some type of expansion/add-on/quest idea where you could go back and forth between FF11 and FF14 and either your character from the one game gets converted to the equivalent it would be on the other game or you have a character made for both games and can switch to that character while in a lobby that is set up in between the 2 games. That could improve the server populations for FF11 by people wanting to return to FF11 to play a little there as well as players that are currently on FF14 that have never played FF11 to explore and play FF11.