Zillow is testing "Instant Offers" in the Orlando and Vegas markets, and it is pretty much the same as what Open Door has been doing in Dallas/Phoenix/Vegas/Atlanta/Orlando/Raleigh-Durham for a while now. They come speak to we agents at conventions and claim they aren't trying to cut us out, because the way it works is the seller (who can sell without showings, staging, etc.) is given an "instant offer" by them, but also a professional valuation from an agent, so in their mind, they are including us.
The offers are very low, from what I've heard, and the fees equal, or in some cases, more. Probably the only sellers that would sell this way would be those who have very distressed homes, so I look at these services as more of a wholesaler with marketing on steroids because of their wide reach.
I've also read on forums that the customer service is super limited with this method, by email only, so no personal touch at all, which obviously, is the cornerstone of a real estate agent's value, along with their knowledge and expertise of their local market.
The day we can take emotions out of selling or buying real estate is the day realtors will cease to exist. Our fees may get challenged, but our profession isn't going anywhere, imho.