FFXI didn't 'add mini-expansions between patches', for a period of several years there was no true expansion at all and just the 'add-on' packs (Crystalline Prophecy, Moogle Kupo-de-tat, and A Shantotto Ascension, plus the three Abyssea add-ons). It was an experiment by SE in possibilities for online delivery of expansions (specifically with FFXIV ironically which 1.0 was still in development at the time). As SE later returned to having a full expansion pack (Seekers of Adoulin), it's pretty clear SE themselves regarded the whole thing as a bit of a failure. So I don't see SE doing anything like that here with FFXIV ARR I'm afraid.

Especially as the 'add-ons' were not even cut down expansions, but just some story/battle content, which in a way we're already getting with existing content patches here in FFXIV anyway.