Mountain View says it's sunsetting the feedreader because it has "declined, " and that turning it off will allow it to pour its energy into fewer products.
Both Podscope and Podzinger allow you to save RSS feeds of your searches to view when your search term comes up again via a feedreader like Bloglines or Yahoo!'
There are third-party apps for feed-reading, but Google Reader remains both the dominant client and nearly the only back-end syncing service underpinning the entire RSS experience (a position the company actively pursued).