Once you exit the house, the kid will be safe. Sabin will then let go of the collapsing house. And whoosh! - it hits the ground like … well, a house hitting the ground.
Sabin also rejoins the party, so that may be something to rejoice about. He can be very strong so is a welcome addition. Buy him a Burning Fist if you didn’t pick one up earlier and let’s leave.
Note that the guy in the northeastern trees will still sell you the Seraph magicite, now for just 10 Gil. It’s own effect when summoned has little use, but the spells are always a nice touch. One friend found; let’s return to the overworld.