They're keeping a tight lid on it for a reason. I don't think it will be an auction since that would pad the pockets of gil sellers.

I think it will be a system based on your participation in the game. Maybe something based on your character's achievement points? Or your total active playtime? Your level? (i.e. you cannot create and boost an alt JUST to claim a house).

YoshiP seems to be adamant that people not "prepare in advance" so this tells me that simply saving up gil won't matter, and if it's an auction or lottery, there's no way to prepare for that in advance. But you can spend time leveling your character and unlocking different achievements, which WOULD be preparing in advance. I wonder if it's not related to the points system somehow. Redeem your points for a housing plot. If you and another player vie for the same plot, whoever has the most achievement points gets it. /shrug

Of course this would be a slap in the face to people with limited playtime.