Interesting, thanks. Am I understanding correctly that point 2 & most of point 3 are risks because of the possibility of either future device compromise, or e.g. quantum decryption technology? These are very general risks, so why do they apply here any more than elsewhere?

I realized I probably should not have replied to the part about OTPs specifically. What I'm curious about is remote trust verification via secure video.

Partially, it's not just future device compromise but also Internet recording. It is best to assume that any communication over the Internet is recorded. From that standpoint, once the keys (not the device) are cracked the internal secret is also disclosed. This was why I recommended ephemeral keys.

By "cracking the keys" a cryptographic break is not always required. It can also happen via disclosure, a weak implementation, problems with the protocol, etc. One can scan a list of recent vulnerabilities for this: session reuse, master secret reuse, session resumption, heartbleed, etc.

I would call these out in particular here, because secrets are being exchanged. If those inner secrets are used to protect (directly or indirectly) multiple messages, the key disclosure becomes more pronounced.

You are quite correct regarding quantum computing. QC is guaranteed to break elliptic curve, DH, or RSA for example. The determining factor is the number of q-bits.

What do you mean by remote trust verification via secure video. That sounds quite interesting. Do you mean facial recognition inside a channel assumed to be secure, as a secondary validation of an otherwise "pre-trusted" party?