Bitcoins fixed supply is not the only thing that gives it the strength it has enjoyed thus. The fact that it inventor is also unknown and that it can't be linked to any known person or group of persons further strengthen and increase the trust that people have about bitcoin.

What makes bitcoin stand out is that it was not created as a model after any other coin. It came with it uniqueness and having stayed this long, it has become an household name for anything that comes after. They can model theirs to look like bitcoin and try to give it a fixed supply but only time will tell if it will do well in any where close to how bitcoin is currently doing.