ES V would have to do something pretty fucking impressive to warrant a purchase. Oblivion isn't even particularly compelling as an exploration or dress up game, since each location is practically identical for a player of equal level, and when it comes to dress up, I can't combine clothes and armour, I have less armour slots, and by the time I can wear something impressive... so is every other motherfucker in the world.
Even the discovery side of finding out what each of the many aspects of the game is like is pretty fucking dire.
"Wow! Stealth gameplay sounds cool, let's give that a go!"
<half an hour later>
"Hmmm, this is quite repetitive. I'm going to try some Destruction magic, that should be fucking awesome!"
<half an hour later>
"Damn, it's just like a bad FPS. What about alchemy? I'm going to travel around, nab some ingredients and experiment with potions!"
<half an hour later>
"Okay, I can't actually experiment with alchemy, since it automatically matches up ingredients, and only utilises the visible effects. Errrr, let's see...what about the Arena? Let's give that a run."
<an hour later>
"Who'd have thought becoming grand champion would be so simple? I can't believe I actually spent a fight farming the arrows my opponent shot into me because I have a bounty of ~8000 and can't get near a store! Hey there's an idea, how about I get caught, and escape from prison!"
<ten minutes later>
"1 lockpick + 17 security + very hard lock = instant escape. It was also kind of handy that I could lockpick the evidence box and get all my gear back while the guards remained frozen in time."
etc.
It might pass the time, but after a while, you come to realise that the long checklist you've worked your way through hasn't really netted a single satisfying aspect of the game.