No way. True Blood has really developed quite a following over its first two seasons, something HBO loves to see since its a paid channel that dosen't need the 'through the roof' ratings of network television.
At this point its the highest rated current show on the network (around 2.5 to 3 million) and has both critical acclaim and a devoted fanbase. It has already begun filming season 3, and I doubt HBO is gonna let this one go anytime soon.