Bad idea. I think the general notion of having guildhouses come up for auction regularly isn't a bad one. That's going to allow more up-and-coming guilds to get houses, rather than simply having them belong to guilds that have been around forever, and aren't necessarily even active anymore.
But, I do think the idea of having to require guilds to re-purchase the lease on their guildhouse every so often isn't a good one. That's going to be very expensive for the guilds, and it's also not very conducive to settling down. However, I might support a proposal that asks each guild to pay a certain set fee (say 250k) each year to maintain their lease upon the guildhouse. If unpaid, that guild's residence would go up for auction. That's not a great amount of tria, and so it would serve as a sort of check on the guild's inactivity. An inactive guild isn't going to fork out that sort of tria to keep a house that they're not even going to use. But I think that would be a better option than forcing a guild to essentially vacate and re-buy it's own house every so often.