I think Vitalik is referring to the currently written up phase 1 spec.
We’ve made progress on the research side recently which points towards a revamping of the protocol. We have a cleaner proposer-notary separation, an alternative to windback, a stronger availability challenge. Some other ideas we are exploring:
- Decoupling collation headers from the main chain, or only explicitly exposing fully notarised collations or checkpoints, maybe using ideas from Dfinity and Bitcoin-NG
- Fork-free proposal chains, and rollback mechanisms
- Variable-size and variable-threshold notarisation
- A new form of signature aggregation
- Strengthened shard finality in case of main chain reorg
- Sidechaining parts of the SMC into a manager shard
In short, the research side of things is in flux. It will probably take a few weeks for ideas to surface on ethresear.ch and for the dust to settle. A new spec (hopefully all round better) may come out in a couple months or so.
The above minimal sharding protocol is a good starting point for implementers. Agreeing on the p2p networking stack (transport layer based on libp2p or otherwise, plus a gossip layer with a channel per shard) seems like a valuable thing to do irrespective of the higher level protocol details.