They are obviously a for-profit company, did an ROI calculation, and there are probably limited options for monetizing their acquisition without charging customers for things they used to get for free.
As Dharmesh would say, if I were a betting man, and I am, I'd give two to one odds they start charging for services that are currently free in the next eighteen months.
This, of course, would open up the opportunity for someone to fly in underneath them. They probably expect that, but of course in the short term there will be a win because it will take time for that person to get the word out.
So I whipped up a quick weebly site: http://everydnsforever.weebly.com/
Submit your email address there if you'd like to get one email if and only if (a) EveryDNS becomes less free than it is today, and (b) a credible, great, free service is created in EveryDNS's place.
(By making this site I am hoping to do my part to increase the cost to Dyn Inc. of changing EveryDNS. Thanks!)
(Edit: grammar.)