Current blockchain platforms, especially the recent permissioned systems, have architectural limitations: smart contracts run sequentially, all node executes all smart contracts, consensus protocols are hard-coded, the trust model is static and not exible, and non-determinism in smart-contract execution poses serious problems. Overcoming these limitations is critical for improving both functional properties of blockchains, such as con dentiality and consistency, as well as their non-functional properties, such as performance and scalability. We discuss these limitations in the context of permissioned blockchains, including an early version of the Hyperledger Fabric blockchain platform, and how a re-design of Hyperledger Fabric's architecture addresses them.