we already know that Chocobos in FFXIV will have bigger role than they ever had in any FF game , we can raise them and used them for races which we already can do in FFXI but here will take extra step to use them in battles and customize their role from tank , DD to healer.
also legacy members will get their own chocobo with special design which tell us that development team unlike FF11 team will add different looking chocobos with time.
now think of the possibilities of the different looking chocobos
will we have different colors each with different ability?
like blue chocobo that can walk on water to reach certain dungeon
green for mountains?
will flying chocobo will ever be implemented?
would you like job specific chocobo?
golden, flaming, evil looking, mechanical, choices are endless

which lead us to: how will we get the rare ones?
new DOL: Chocobo Breeder?
rare drops from bosses
buy using seals or whatever
reward from achievements
find it in the wild and capture it

feel free to discuss any of the above points or add any you like
this is chocobo-land