Cheers couldn't have sold too badly or they wouldn't have made it through so many season sets. Perhaps they're staggering the releases now or are simply slow to announce the next Cheers set. Probably taking a long time to count up the number of extras that the set WON'T have. :rolleyes
If they don't release season 8-11, then i'll not "support" any series any more! In the future i will wait untill all seasons are released!!! The companies ruin their own business when they make their customers angry!!!