to whom it might concern ... the issue at WHATWG is still open for discussion and there seems to be some interest around the idea ... to help anyone playing around with the proposed Symbol.structuredClone solution I have created a recursion-aware polyfill that makes things "just work", it's on GitHub and npm as symbol-structured-clone.
It's currently targeting the browser (main thread patches, Worker patches, paches in workers too) and you can see how it's being tested too.
I keep believing that resurrecting something meant to be just data representation of a proxy or any other non clonable references is an implementation detail easy to delegate to user-land code, but something that avoids constant pain around proxies or special references that can't survive a postMessage roundtrip or a structuredClone operation would be more than awesome.
Around the resurrection concern, it's also impossible to pass classes around so that if something was a Proxy of some special class in a worker that might as well never exist on the main thread and with WASM targeting PLs that also do roundtrips that's most certainly always the case.
As the implementation detail is also hidden from users, I'd love to move the symbol proposal forward but I think both TC39 and WHATWG should agree that it's time to give users that ability and that the polyfill can help out testing things or making users happy until all vendors/engines are onboard and shipped the real implementation, thanks.