You can tell the ordering of transactions in the absence of a trusted third party. There's an entire body of research dedicated to ordering transactions called

You can tell the ordering of transactions in the absence of a trusted third party. There's an entire body of research dedicated to ordering transactions called Byzantine fault tolerance, but all of them require trusted parties to maintain consensus. Cryptocurrency is the first time we could really escape that. As for infrastructure, things like the lightning network will provide scalability, things like starks and bulletproofs can help both privacy and scalability, decentralized exchanges help accessibility.