> This seems like a truly unreasonable level of political skill for nearly any setting. We're talking about changing every endpoint in the Internet, including those which can no longer be upgraded. I struggle to think of any entity or set of entities which could plausibly do that.

Case in point: IPv6 adoption. There's no interoperability or negotiation between it and IPv4 (at least, not in any way that matters), which has led to the mess we're in today.