If anyone is working on Raft already I'd be happy to discuss the details. I am fairly new to the PostgreSQL hackers ecosystem so cautious of starting work in isolation/knowing there is no interest in accepting the feature into the trunk.
Putting aside the technical concerns about this specific idea, it's best to start by laying out a very detailed plan of what you would want to change, and what you see as the costs and benefits. It's also extremely helpful to think about developing this as an extension. If you get stuck due to extension limitations, propose additional hooks. If the hooks will not work, explain why.
This is exactly what I wanted to write as well. The idea is great. At the same time, I think, consensus on many decisions will be extremely hard to reach, so this project has a high risk of being very long. Unless it's an extension, at least in the beginning.
