#6 Johnny Gargano
How do you mention one without the other?
It already looked likely that Gargano may be main-roster bound when he was released from NXT after losing his contract in a match against Andrade "Cien" Almas shortly after their five-star match earlier this year. Ever since then, Gargano has proven himself as one of the best wrestlers in the world in his feud with the aforementioned Tomasso Ciampa - and while the pair will undoubtedly always have unfinished business, you'd have to think one or both may be main-roster bound very soon.
Gargano's main roster arrival may, like Ciampa, depend on how his Last Man Standing Match at NXT TakeOver Brooklyn goes - but if he loses, you'd have to think it may be Gargano's last NXT appearance unless he gets one more shot at the title - maybe in a contract vs title match again.
One way or another, Gargano has been touted as the next Daniel Bryan and could very well move to the main roster very soon - but you wouldn't put it past Ciampa following him there and ruining his arrival...