The “most obvious” reason why Google Code might be dumped is that it hasn’t added a new feature since 2011, InfoWorld notes, though there is also the rise of GitHub, which has accelerated the practice of coding as a “collective and social” endeavor — exactly what Google Code had set out to accomplish.
Indeed, the last feature added to Google Code was the addition of support for Git, allowing projects to be moved to GitHub from Google Code more easily.
Also notable: As of Jan. 15, Google Code no longer supports downloads. And the official Google Code blog talks more about open source generally than Google Code itself.
Should Google decide to turn out the lights on Google Code, the usual process is what appears to be already at work here: A period of stagnation, followed by an announcement, then a transition period for users to move off the service, with the service shut down at the end of some months.
If this is like most Google shutdowns, by the time the product goes away, few will remember and even fewer will miss Google Code. Whenever that time may be.