I know this may sound stupid but hear me out.
What if in the social panel there was a tab for server or cross server pvp listing. It would act kind of like what the LFM tab would except it would list your name, or the person who posted their name and you would double click the name, or wait for someone to click you. Then a window would pop up and say:
"("Insert name here") would like the challenge you." [Accept] / [Deny]
I hope we can get the implementation of a posting board based pvp organization.
Other idea: Seperate PVP server that would temporarily transfer your toon to that server for lobby based dueling.
Hopeful list of supporters: