I feel its obvious we will finally explore the "oblivion".
Could be a good way to bring back dead characters for one last look. It would be a complete copy of Once but hey it could work. It was also explain why Nina's return is being kept under wraps.
What do you mean about the Nina part? Cus she'd be doing Katherine?
If we DO see Katherine in Hell, it's just absolute, utter, embarrassing proof that TVD is literally THE most unprofessional set in-terms of set-leakage. When 12 yr old girls are posting MAJOR spoilers in highly specific, intricate detail MONTHS before completely coming true, verbatim...on their goddamn Tumblr's, somebunny don't know how to run a staff. Like the Sleeping Beauty Spell/6 finale.
It's been out there in rumor land, which lead to all the *beep* web tabloids, that Nina was reviving Katherine/playing a villain/against Damon since early Summer. And it makes perfect sense, cus this way, fans get to see her, so she can further limit the time she plays in Elena's skin (to avoid the Delenaing, neither actor is willing to do).