I wanted to explain this a bit more. Initially this started out as defining a standard extensible API for data, such as chain id.
Then I also wrote up a draft, which includes EIP-210 (blockhash) support in it, but never pushed that change.
Currently I am considering changing it into a meta EIP describing the guidelines how data contracts (such as chainid history – however @fubuloubu has a nice proposal for that, blockhash, logs, etc.) could work.