Oh my. Now we're talking about the progression of punk.
What became "new wave" was universally called "punk" originally. As some of the punk bands became more mainstream and signed to major labels, there was a widespread uneasiness about still calling them punk, so this new term "new wave" was coined as a catch-all for the bands with the poppier, more commercial sounds. Talking Heads, Blondie and the Go-Gos were definitely punk originally and then were definitely new wave over time, for example. Bands like the Clash didn't really change what they were doing -- the market matured to where their original innovations became mainstream normalcy.
aka_twitch wrote:
Take the Clash, replace the frustration and snarl of punk with a smart playfulness. What do you have? The Talking Heads.
None of these categories is very well defined, so I'm not willing to concede that argument to you. The Clash had a lot of smart playfulness too and The Talking Heads had some frustration and snarl, especially early on. The Clash were street punks, while the Talking Heads were art punks. Just variations on a theme.
And to get more on point, ska is just as difficult to track and define into neat little categories. The Toasters are usually classified as the beginning of the 3rd wave, primarily because of chronology, but they also often get classified as 2-tone, primarily because of sound and approach.
Going full round, The Clash are generally accepted as having an influence on 2-tone and making some minor contributions themselves. But they are also universally classified as punk and not ska.