Pause. Because when I need to stop playing for a sec, I need something to pause the game while I do it. All they have to do is not allow you to use items from your menu while in combat, simple as that. If in combat, the only way to equip weapons or use items should be from your quick menu.
There's a pause button for that (esc or start, depending on the system). I would hoever prefer it to be real-time, I think it would make fights that little bit more dangerous knowing you can't just freeze the action to pop a bunch of potions before going back in.
I think it's a given that this won't be happening, however I would like to see it made easier to do it via mods (now that I think about it, I'm not sure they ever got it working properly in Oblivion, but I know they tried).
That's just my two cents. I don't think they will, or even that they necessarily
should, but I'd like it.
EDIT: Just thought I'd add that I'd like it if
all gameplay elements were done in real-time. Conversations, etc. I think it could create some very interesting effects.