The point of dnssec-chain-extension is to enable browsers to use DANE without performing additional DNS record lookups and incurring the associated latency pena

The point of dnssec-chain-extension is to enable browsers to use DANE without performing additional DNS record lookups and incurring the associated latency penalty. We can invalidate all the counter points if DNS servers supported additional answers or push. With DoH we get DNS push and a browser could do DANE without incurring the associated latency penalty. They could peak ahead in the stream and see if a DANE (or SRV) record exist. No latency, no middle box, no additional secure connection, no dnssec-chain-extension, no certificate pinning. DANE support in the browser would then be purely a optimistic code path that improves the security if the DoH server happens to send it.