Don't forget that there will be airships coming so people won't be completely flocking to the Ul'dah company out of convenience. There's tons of people that are going to go to Limsa or Gridania if you ask around.

BloodLotus, I got from that that they would be "disabled" but they are still saved in the event that we can eventually change companies.

はい、なくなってしまいます。
ただし、将来用途が発生する可能性も踏まえ内部データとしては保持されます。
Yes it will be gone, but for future there may be possibility to use them so the internal data will be stored.