So here is my idea.
What if they allowed exploration of enemy territories but made all NPCs hostile and allowed any PCs in that world to attack you at will.
This would be in keeping with the Elder Scrolls focus on exploration and would allow for a limited form of FFA PvP.
Obviously it would be extremely hard to survive in a world where everyone was hostile. But that's the fun of it. Stealth characters would be especially good at this because they could sneak around the enemy world. This wouldn't be a major part of the game but it would a be fun little add on that would add to the experience of the game.
What do you guys think?