He's a perfect 3rd seamer in my opinion. He would be the final missing piece in an ATG attack.
Imagine Steyn and Rabada opening the bowling together, should the opposition survive the early onslaught having a guy like Starc running in with a reversing ball would be a sight to behold.
Having someone who can take the last 5/4 wickets under 60/50 runs consistently would be amazing for any attack. Yes he might get bashed for "bullying" the tail by cynics, but his country men and purist would appreciate him more. It's how SA won the number 1 ranking in England 2012. It's how Australia always beat us as well, a wagging tail. In fact it's how we beat Australia for the first time in Australia as well. A wagging tail is very dangerous these days.