At 3000km, that's shorter than even a severe-duty oil change interval. One long trip and it's done. Seriously, say I wanted to drive from Dallas to Las Vegas; the battery lasts just long enough to get me there in one shot. Sure, the rechargable pack lasts long enough for the short drives once I'm there, but the return trip is going to suck with the repeated stops for recharging, especially with the lack of SuperCharger stations along the way. So by the end of 2015 I'll be able to make it, according to Tesla, but what do I do until then? I suppose if I can afford a Model S I'm probably affluent enough to pick up a plane ticket instead?
This "battery swap" is going to be nowhere near cheap, and we're talking about adding 220lbs to an already relatively porky sedan. I think I like my chances with next-gen rechargables better than this.