To me, it'd defeat the whole purpose... NXT basically builds certain people up to a point where they already have a rep and familiarity with the WWE audience once they hit Raw or SD... making it a separate brand would just have certain guys running in the same circle. They'd never get a shot to work with the upper tier, they'd just stay wrestling each other in what definitely would be known as the #3 brand in the company. It'd be "the C show", like back in the day when they did house shows and some poor city would only get to see Tito Santana in the main event, while other cities were getting Hogan, Macho, and Warrior.
it already is the C show. more like the C- minus show, seeing how they treat them as their minor league.
im saying, if they officially made it a major brand, the wrestlers wouldnt be stuck there. they would be apart of the annual draft and wrestlers would jump to NXT the same way wrestlers leave.even if it was a step below raw/smackdown like the WWECW. cuz NXT basically seems like what they were tryna do with the failed ECW re-launch.
they could have wrestlers from the "upper tier" shows jump to NXT, the same way they jump off of it. this would especially be good for the guys who either aren't doing much on raw/smackdown, or are just sitting in catering. basically a bunch of people who are on their way out once their contract expires. not to mention the main eventers that are just floating around. if they treated the NXT belt like an actual world title, they could've easily just sent dean ambrose over there and let him do his thing. sorta like how big show, kane & them would get runs with the ECW title. but since NXT is seen as wrestling school, they left dean with no other choice but to leave the company altogether.
and NXT wouldn't have to change anything. they just need to boost their status. that way it could really be the renegade brand that they try to sell it as.