According to the newest September FFXIV census, people with high subscription days are only a small percentile of the player base. I do not think FFXIV wants to lock housing behind this system, which will only result in disappointment among new players who genuinely wants a house for their own sake or FC. Meanwhile, I am pretty sure majority of the house monopolizers are veterans, who can simply give their existing house to their alts just so that they can purchase more. This would not solve the issue, not to mention additional resources and efforts in manage the time slots. I much rather they put more effect in actually fixing the issue, instead of being encouraged to apply more temporary band-aids.