Bitcoin is the only truly decentralized digital currency which has grown spontaneously as a finely balanced equilibrium between miners, coders, and users, none of whom can control it. It was only ever possible to develop one currency based on this design, because once it became obvious that it is workable, any attempt at copying it will have been a top-down and centrally controlled network which will never escape the control of its creators. So when it comes to bitcoin's structure and technology, it is highly unlikely that any coin that copies it could replace bitcoin.
