While discussing how the newest FFXIV patch hooks in players by introducing characters and worlds that were in FFXI, Yoshida mentions that several staff members for FFXIV are former FFXI players.
In an interview with Game Watch about Final Fantasy XIV Version 7.1, Naoki Yoshida mentioned that the staff who worked on FFXIV Echoes of Vana’diel also played FFXI back when that was the main MMO of the franchise.
If that happens, then FFXI players might get annoyed that their game’s story changed as a result of FFXIV.
Some members of the FFXI development staff are also working on the Echoes of Vana’diel series.