If TACK can rewrite the trust model away from the CA and into the state of subsequent connections, we won't need the actually CA. Self-singed certs are equally fine to establish trust after first connection.
If however we do use CA's as the trust model in order to trust the first connection, then TACK is nothing but a policy system to attempt keep CA honest. Users would still need to put their trust to third-parties that they never meet, and who's priorities and objectives are unknown.
I see TACK as a decisive mitigation for the biggest danger posed by CAs today (that they enable global passive adversaries to conduct dragnet surveillance), and as a step towards a workable web-of-CAs system.
I do not believe in pure peer-to-peer schemes as workable solutions, but I do believe that we could in 5 years have a system where I can trust ACLU first, and then Verisign as a fallback.
If however we do use CA's as the trust model in order to trust the first connection, then TACK is nothing but a policy system to attempt keep CA honest. Users would still need to put their trust to third-parties that they never meet, and who's priorities and objectives are unknown.