I posted a top-level comment[1], but basically HTTPS-only, aside from throwing old sites under the bus, would not have helped.

[1] https://news.ycombinator.com/item?id=21726617

> and in case I'm totally wrong, what mitigations are feasible? More trade war such as by compelling ISP's to null-route Chinese businesses like Baidu.com as a form of sanction?

Probably something like this, but I'm afraid of where that would lead.