When a home is sold, the realtors typically get 6% of the sale price. For a 1 million dollar home, that's $60,000. Why so much? I think it has to do with the value of the human touch for large, infrequent decisions. A homeowner might only buy and sell a few homes in her entire life, and if she screws it up she could be leaving a lot of money on the table, or even worse, could end up with a home that she doesn't want. The realtor can make the sale on an emotional level, something that's hard to automate.
I see startups like haus.com that add technology like transparent pricing. This is great, however I don't believe that will eliminate the realtor or fee.
On the other hand, what if there was a trial period and after moving into a new home where you could back out if you found out something you didn't like? This could fit well with the opendoor.com model where they buy and sell the homes, turning a two sided market into two one sided markets. This is a startup to watch.