Nothing will ever replace Google Reader once it passes into digital oblivion, but there are many, many alternatives to select from, so chances are there's something out there that will be good enough. Quite RSS, for example, replicates the look and feel of Google Reader, while also adding a few improvements of its own.
One thing to get out of the way is that it's a desktop app, not an online one. That said, it's available for Windows, Mac OS X and Linux and is based on the cross-platform UI framework Qt, which means you shouldn't have any problems running it.
As this story on Addictive Tips notes, the appearance is very similar to that of Google Reader — you can even open up stories in different tabs, replicating a browser-like environment. It also supports the import / export of feeds via OPML and a healthy number of shortcuts to change the layout or switch to full-screen.
I'm still using Google Reader for my feed-reading — and probably will until it gasps its last breath — but before it's retired, Quite RSS is one option I'll be seriously considering.