i think at the moment almost all social networks are similar at the platform level, facebook is a bit above only for the vast number of registered users, i think sphere will be successful if they can offer a large amount of services and options and mobile apps lighter and faster than competitors
The most important things which determine whether the new social platform succeed or not are:
1. Its interface (friendly or not)
2. Its ability to spread out as more users as possible
3. Its applications in daily life (Sphere can do that, at least in crypto-ecosystem).