I think this is a great idea. In fact, nothing may be needed except to limit UST to ($1 worth of) LUNA conversion only when market cap of LUNA > market cap of UST to dig out of this whole mess.
And of course put some other limits as training wheels (like limit amount of LUNA that can be minted per X time) for now.
But we might see organic re-peg if we can get crowdsourced LUNA buying.