Elmer over at ZAM has written up a summary from three popular Japanese news sources (GameWatch, 4Gamer, Famitsu) who all got the chance to sit down with Hiromichi Tanaka and Nobuaki Komoto after the Square Enix E3 press conference on Wednesday.
In the information given, Tanaka mentions that initially, they wanted to add a second door into the Mog House that would allow players to exit into the new Final Fantasy XIV world of Eorzea. Due to technical difficulties however that was not possible.
Other things that are mentioned include the possibility of transferring over linkshells from Final Fantasy XI along with character names. These are possibilities they are looking into and are not currently set in stone. Server sizes and the hopes of exceeding the number of worlds that Final Fantasy XI has is also something that the FFXIV team is looking at.
Check out the full write up for more information