As reported by Mike Johnston in
The Online Photographer, the introduction of the K-7 means the end of life of the K-20D.
Now, Pentax has said several times that the K-7 is not a direct replacement of the K-20D, but rather a "new concept". In this view, it migth be possible that the K-20D has a successor later in the year, maybe in the form of a K300.
But fact is that the K-20D can be considered out of production. Yet, I cosign the comment above: the K-20D will be a most capable dSLR camera for years to come, and unless you suffer a severe form of acute lastitis, you could happily live with it for a longtime. For instance, I own a K10-D and it works fine, outcompeting my photographic capabilities pretty much always.