Not sure where you heard what you heard ...
and while I can certainly understand not liking it (personally I think it's fab, but it's certainly absurd to the point of being polarizing)
... it's one of the highest rated original productions on Adult Swim, the network execs love the caliber of guest star that exec. producer Bob Odenkirk brings in to the production ...
and Season 4 begins This Sunday
http://vimeo.com/3056385
So, at the very least it's not cancelled.