I don't agree with this thread that Seinfeld is going off.
I think it had a bit of a dud season two years ago but that the last two seasons have more than picked up the slack.
I think we're one season behind here in Australia - we've just seen the Elaine's bad dancing episode. Anyway this current series that we're seeing has had some of the best episodes ever.
The already mentioned Elaine dancing episode (didn't catch the name); the Bizzaro World; George having to sit on the Susan Memorial Board.
It is easily the very best thing on television. No other show has the variety or cleverness in writing. One of the best things about Seinfeld is the multiple storylines - sometimes five or six in one episode. No other show does that on a regular basis.
I think, if not already, that in the future Seinfeld will be ranked among the very best TV comedies ever!!
In answer to your question "Why does it Shrink!!?" - it just does.......