Speaking about how slow Bicoin is. Why Bitcoin can't be just settlement layer for different fast protocols without legers? What will drive developers to code for those various "without own ledger" protocols in this case ?
That can be done in centralized environment very similar to the visa and MasterCard network. Where they are the providers of settlement layers and their APIs are being used by various participating bodies. Bitcoin is decentralized and unlike other settlement layers, it has its own value.
However, I have seen some ICOs trying to build private and customizable blockchain. But it is not achievable for bitcoin.