Glee is very popular and a big money maker for Fox. However, I don’t see the show being on 10 years like American Idol, CSI, NCIS etc. The reason I believe it won’t last that long is because these kids are going to be replaced once high school is over next year....the writer and others have said as much. Once they bring in another batch of kids the show MIGHT make it one last year. It is a four year (season) show and that is it.
Unless things have changed, the show's creator said that the characters would not graduate. They would be perpetually in high school.
High school was over for most of the cast years ago. TV is notorious for casting 25-year-olds to play teenagers.