An interesting summary of the RSS/Atom feed reader market
http://www.rumproarious.com/2013/04/18/how-large-will-the-payed-feed-reader-market-be/

Especially note this comment:- 
I wanted to determine the number of people who use RSS on a monthly basis. Also, how they use feeds is important. I only want to estimate the people who are using something that works like Google Reader. There are a lot of people who use RSS when they use something like Flipboard, but don’t know they are using RSS.
Because of course there are numerous use cases for feeds that don't necessarily look like direct consumption by an end user as relatively raw untouched content. Flipboard, Pulse, Currents are all examples of this. So too are backend services like dlvr.it

The bottom line figures.
- ~ 65m regular users
- ~ 2.6m potential paid subscribers based on typical conversion rates for current freemium services.

Of course, subscriptions are not the only possible source of income for a feed reader service. There's also adverts, selling the user interest data, selling the reader software, selling the aggregated data and probably several others.  

Meanwhile, Larry Page in his earnings call talked about Google continuing to work on speculative products. But of course he didn't really talk about closing speculative products such as Google Reader.