They should incorporate a reward system for it like Rewards for the worthy. Win x many duels and you receive emailed rewards. They could also put in a wager system between the duelers. When you duel someone a box opens asking if you want to risk gold, you can then enter in an amount. The person that's challenged sees the duel box similar to a trade window and has two options, duel them betting the same amount, or duel them with no wager. Then you could still duel just without the side bet. Duels within the same faction would drop health to 1 to end the duel. Dueling in Cyrodil would be to the death. Dueling in Cyrodil would open up an instance for just those two people, this would ensure that it's a fair fight with no help from other players.
Hopefully at some point dueling will be added regardless of wagers or rewards.
NA Server - Kildair