I am starting to be concerned that the ability to use DNS to block tracking, malware, and advertisements is only going to prove temporary.

There appears to be more effort generally to secure and encrypt the entire DNS system. This is really good and should be applauded and supported. But it will come with a downside... once we reach a future in which DNS records are encrypted end to end, and DNS records are only valid when signed by certain keys, and authenticated NXDOMAIN records... then things like Pi-Hole start to become more difficult as for security of DNS we'll have lost the convenience of changing the answers.