Expand on TEEs?
This certainly is an awesome list!  Great work :-)

I note the inclusion of Ekiden, which has since become part of the [Oasis Protocol](https://oasisprotocol.org/), one of the key contenders in the space which combines blockchain and TEEs (Trusted Execution Environments).  Since this TEE-based approach is potentially a real contender to the ZKP approach to blockchain privacy (although I'm aware there will be varying opinions on that), it might be worth expanding on this.  In addition to Oasis, here are some others which I have discovered during my research:

- https://taxa.network/
- https://scrt.network/
- https://www.substratee.com/
- https://iex.ec/
- https://www.teechain.network/
- https://trustkernel.com/uploads/pubs/shadoweth.pdf (don't think this one evolved beyond the research stage)

Hope this helps.