I don't think the "open core" model is in their best interests. Look at a company like Zenoss, where their OSS version is their biggest competitor. It doesn't make sense for ES to do that.
Now marvel[1] is where they've started monetizing and I'm sure they make a good bit of money from "professional services" teaching companies how to deploy ES at scale. Hopefully they pull it off, as the world needs a good competitor to splunk. ES has the backend tech, but kibana has a loooooong way before it rivals the interface for searching splunk. Here's to hoping!
Marvel is quite interesting. It is a product everyone _could_ build on their own (basically, it is Kibana over their own metrics data), but at that price point, there is no reasonable reason to do so.
Now marvel[1] is where they've started monetizing and I'm sure they make a good bit of money from "professional services" teaching companies how to deploy ES at scale. Hopefully they pull it off, as the world needs a good competitor to splunk. ES has the backend tech, but kibana has a loooooong way before it rivals the interface for searching splunk. Here's to hoping!
[1] http://www.elasticsearch.org/overview/marvel/download/