High school musical 4?

im not a fan of the movies, but my whole family is addicted to it. but i dont understand how a 4th movie going to be as apparantly good as the first 3?i mean triology, some movies survive, but the high shcool musical isnt that good. i mean look at the terminator series, they had such a down fall after the first 3 films. the only movie that probably can pull it off is ice age and shrek. am i the only one who has this point of view on films today?