That would be really cool. Such a system could totally replace the role of the CA in verifying that a public key is attached to a particular domain name.
I guess we'll still need CAs to perform detailed identity checks in order to issue the so-called 'extended validation' certificates, for high-security web sites.
I wonder how to get everyone to switch though? The existing CAs will lobby against any change. One advantage of getting certificates via DNSSEC would be that it would finally be possible to actually *revoke* a certificate, something which is basically impossible with the current system, since no one configures their browser to check the CRL of each and every CA that it trusts...