If their is ever going to be a D3, I think what they should do, is have a quest. This quest would have you square off a random popular build of any character class from D2. If you win, you will open a specialized area for strictly PvP combat. This would stop PK characters in games, and such.
This area will be inspired by old roman collusems. It will have some options before battling, such as wagering (with gear, gold, picking winners, and loosers, ect.) one on one, team, and free for all, king of the hill, (where it's all against one player character or npc boss) timed matches, life or death, (same as H/C, character dies, it's for good, but only PvP) maybe even fight in ranked torneys against other players, and/or popular builds, bosses, ect.
Other notable options, could be:
Stats:
Win %
Loss %
Total Kills
Naked Kills %
Fastest Kill Time
Ranking for class, winning streaks
Clan Name (if any)
Seperate chat channel, where you can watch a PvP in progress, while chatting with others. Maybe even wagers between spectators, special unique items for torney winners. Also a player can click on another character to see stats, as well as gear, (like maphack did) and so much more.
The possiblities are rather endless.