A secure DNS is valuable whether or not we get rid of CAs, since CAs rely on DNS queries to verify domain ownership.

And if we have a secure DNS, then CAs are completely redundant. I'd much rather trust a handful of domain registrars than a handful of domain registrars, plus 100 random questionably competent organisations all over the world. Especially when any one of them can generate keys for every domain on the planet.

"Secure" doesn't mean anything. A closer (though still imprecise) descriptor is the CIA triad --- confidentiality, integrity, and availability.

A confidential DNS has real value. Without it, ISPs actively monitor customers and sell analytics about usage upstream; there are other problems, but virtually every US user faces that one. It's hard to imagine wanting to trade confidentiality off.

A high-integrity DNS is a more dubious proposition. You'd obviously rather have integrity than not, ceteris paribus, but we have effective mitigating controls for DNS forgery, so you might imagine trading it off.

Availability also sounds like a no-brainer, until you remember that almost every other component of the networking stack also has availability issues. You might not want to trade anything at all to get a more highly-available DNS, if you're going to be just as susceptible to DOS attacks because the current DDoS meta is application-layer anyways.

There are a bunch of different approaches to securing the DNS, and they make different tradeoffs.

DoH focuses on confidentiality, and has bank-shot benefits to integrity (because it breaks forgery attacks from on-path attackers). Confidentiality is its primary purpose and it trades basically everything else off.

DNSSEC makes the opposite tradeoffs: it's exclusively for integrity, provides no confidentiality, and highly prioritizes availability (that's why it has elaborate authenticated denial systems).

Depending on what you want to achieve, "secure" DNS can make sense and actually get deployed and used, as DoH is, or it can make almost no sense and see almost no uptake.

It seems a nice thing to have indeed, but domain registrars have already a history to cede control and bend to $GOVERNMENT. We have countries already trying to MiTM all their citizens by mandating CAs injection in every device under their jurisdiction, what would be the defense against this threat in a world where registrars hold the keys to TLS encryption for the web on the TLDs they own as root? I'm not that expert in this field so I really would like to learn if it's possible.