Well, there is already some FFXI tracks in the FFXIV game files which were used for the two FFXI-crossover special events that have run in the past, so it wouldn't be too difficult to turn these particular tracks into Orchestrion rolls (Feast of the Ladies from A Shantotto Ascension (curiously this is on the FFXIV OST under the title 'Reign of Pain'), the original battle themes Battle in the Overworld #2 and Battle in the Dungeon #1 from the base game, and Recollection from Chains of Promathia, and the nameless 'Quest complete' fanfare).
Whether they could add more though is another barrel of moogles (my choice would be Vana'diel March, Metalworks, the four city themes, Ronfaure, Gustaberg, Sarutabaruta, Selbina, Mhaura, Kazham, Awakening, A Realm of Emptiness and Bandit's Market), but anything is possible. :)
