There are many segments in real estate that are ripe for disruption, Zillow is not the end all be all of real estate. Take cap rate calculation for instance, this is something very important to real estate investors, but Zillow hardly has a product that addresses it and tries to predict it accurately. Their strategy seems to be let's go after mom-and-pop buyers who just learnt how the internet works. If Zillow could bring in a fraction of tech you see in a product like Facebook or Github for instance to the broken industry of real estate instead of just showing pictures of properties with a few other metrics next them then the industry could be disrupted.

[1] https://caproi.com