Pretty much yes, unless ISPs start blocking IPs as well. We haven't seen this in India (at least yet)

That also gets tricky for them, when say IPs are from Cloudflare, AWS or other cloud-scalers and CDNs.

Nations will struggle to block the IP ranges for big players like that without blocking a lot of stuff they don’t intend to.

In most cases: no. ESNI is still a draft and most sites are identifiable by IP only.

I'm wondering this too. The article claims some of the connection are proxied. However if it's a big site that uses a set range if incoming IPs, I feel like blocking could still happen at the TCP level (and maybe catch a bunch of other unrelated sites if it's on a shared hosting solution).

Have used ESNI to successfully circumvent this in the past.