I would think it's less likely because it's such an illiquid asset. It's not like shares where you can just liquidate on a dime. Also the potential destabilizing nature it would have on the whole economy and therefore the bank's own stability.
I learned from see_change the other day that "margin calls" are possible for CIP loans, but I've never heard about it happening in residential. If I'm wrong I'd love to hear about it as I've wondered the same myself.