I can't believe what some people are writing. Like seriously. Almost every aspect of the camera is an improvement over the K20D. There's nothing in the K20D that is worth saving it for (you can't even make the tried, and often true, "fewer MP = higher IQ during high ISO" argument, because the MP is the same).
So (a) yes, the K10D->K20D line is dead; it's been succeeded by the K-7 line. And (b) whether or not one should want to upgrade depends *entirely* on *your* needs, not the needs/wants of other members.
Take FPS; any nature photographer or sports photographer would call 3 fps a joke, and a 5.2 fps good/acceptable. I know a guy who bought a 30D over a 5D because of the FPS. He's a birder. If that's important for you, it's a no-brainer.
Take Live View. If you do macro photography, or, like me, do a lot of tilt photography, or astrophotography, you know how useful Live View is in nailing the focus. And frankly, Live View on K20D sucks so hard, it's too bad it's not even funny. The lowest end Canon Digital Rebel has Live View leaps and bounds better than the K20D. If that's important to you, then yes, it's worth $1300 MINUS whatever you can sell your K20D for (important information you left out). And let there be no mistake, there will be absolutely *no* reason why you would want to keep your K20D around, unless you want a sub for the K-7, in which case, the question you have to ask is not whether or not the K-7 is worth $1300 but rather whether a K-7 + a K20D as its sub is worth $1300.
Take mirror lockup. Again, if you do any kind of shooting where pinpoint sharpness is of utmost importance (extreme macro, astrophotography, etc.), then mirror lockup is crucial. No brainer.
And my favorite: digital bubble level. As a shooter who pathologically ends up tilting every single one of my shots by 1-2 degrees, always to the right, that by itself is worth almost $1300
If none of those things are important to you, well, then, you have your answer. You don't need to upgrade. Stick to what you have and buy another lens :-)