A great idea, but it still leaves the possibility for performance issues prior to an admin's ability to address is. Some like two 4gb blocks might work better: if you get within, say, 200mb of storage limits you remove the first one and trigger an email/text/whatever to the admin, that way they can address it before it goes further. It's an early warning and automated solution. Then, if the situation continues, the second 4gb block is also automatically removed with another message send to the admin. Nothing fails silently.