In terms of a GSoC project, it would have to be in terms of picking up the bits and pieces and continuing to work on them. There’s certainly a good amount to do I think, but whether it fits together well enough as a GSoC project I can’t say. I guess a really quality proposal would demonstrate that it does: all the issues and outstanding points are in eyesight, a question really of doing the work to tidy it back into a plan.
Hint: try to follow the history back to the beginning and draw up the requirements fresh: David has done a lot of the work, so what’s outstanding, and what are the issues? What’s the Backwards Compatibility and migration story? What’s the plan if we can’t proceed the request object modernisation? If you can get 100% clear on all that, then you’d be able to write a convincing proposal — but it’s going to need to be sophisticated. (That’s a challenge, but maybe one you’re up for.)