As I understand things, Zillow's approach wasn't a corner, but rather an attempt at arbitrage/value-creation. They were pretty sure they had an edge at price-estimation and had enough capital to be able to simultaneously offer sellers execution speed and offer buyers a price they would accept. It is a market-making play.

My impression here is that Zillow has re-evaluated some part of that calculus and decided to pull back. I hope that they'll be able to retool and revisit the approach after learning expensive lessons, as it is my impression that there should be real value here for all concerned.