I dont know what GW3 would entail in terms of game play . I do know I got tired of grinding multiple currencies after each new story was added in GW2.
A redo or modernization of the original in terms of graphics, the addition of a market like GW2's , for selling and buying and the addition of a dodge feature would sell me for another 19 years on GW1.
I'd be in if it was something like this, GW1 was always the better game IMHO.