What if no body shows up at my son's party?

My Son is 7 next week and I would love to throw him a party at the local community centre. The only thing is non of the parents at school really talk to me and another boy is having a party on the same day. I have tried to persuade my son to do something else but he has got his heart set on a big party. We haven't really got any other children in the family so if no one comes it will be a disaster. My friends said they will bring their children, which guarantees 4 kids but Im petrified that out of the 30 kids we are inviting, none will show up and it would break my son's heart and my own.