Of those mentioned, it's likely to be either Dawson or Gamboa. However, neither of those guys are that young & 4 years is a very long time in boxing. Alexander, Ward & Dirrell are distinct possibilities if one of them wins the super-six. The thing is the P4P rankings are invariably US-dominated (or certainly dominated by fighters who've fought on US TV), otherwise I'd make an argument that if Hasegawa can deliver on the promise he's shown, he could well be up there, he's already in my top 10.