The brand extension should return.
Here are some reasons why.
More talent and less over exposure. Guys like Tatsu, Riley, Ryder, Tensai, Gabriel, and Kidd could get their mid card spots like some of them already had before. Think of what these guys could do with a Cruiserweight belt and a time slot on Smackdown.
Less Cena, Punk, Ryback, Orton, Big Show, and Sheamus. I have liked all at some point and think Sheamus is great but I'm so sick of them.
A lot less promos and more matches. Last nights Raw only had five matches and one was a divas match which didn't even have a meaningful ending. We went from having eight matches in two hours to five short ones in three hours.
Tag teams would be big again. It will probably never be like it was back when E&C, Hardy Boyz, Dudley Boys, Too Cool, Kai En Tai, Hollys, T&A, and APA were around again but it could still be relevant. Smackdown used to have London/Kendrick, MNM, Hardy/MVP, Duece N' Domino, Los Guerreros, and Basham brothers while Raw had Cade/Murdoch, Cryme Tyme, La Resitance, Booker T/Goldust, Orton/Batista Haas/Benjamin... My point is both shows always had a lot of great tag matches every night.
Women's devision. Smackdown had cruieserweights and Raw had women. Trish, Lita, Stacy, Torrie, Molly, Victoria, Kim... All could wrestle good except Stacy and she was still better than anything today. Eve and Kaitlyn every night sucks. The Women's Championship used to mean something and the divas were actually feautured. Stacy would wrestle Torrie in a Braw and Panties match while Trish would have a good one fall match with another diva that same night.
Smackdown got so many guys over. We had Eddie, JBL, Cena, Benoit, Rey, Booker T and so many others become main eventers on that show. Over on Raw they would have just been burried by HHH so he could fued with his buddies HBK, Nash, Batista, and Orton. They also had Undertaker getting attacked by some terrorists Muhammad Hassan summoned which was pretty funny.
Raw had the guys who HHH burried like Kane, Booker T, RVD, and Y2J stealing the show every night.
We have Main Event and Superstars which could be used as a way for guys to interact cross brand unlike Heat and Velocity.
As far as single brand PPV's go, I don't like that but they could defend only one of the main belts at each PPV excep the big four which IMHO would make WHC meaningful again.
Obviously brand splits have cons but in the PG era where promos suck and it's the same boring guys every night, what can anyone do to make it better? The way I look at it is Super Cena/Sheamus + Khaliswoggle or more talent, better matches, and less of the same boring stuff every night.