The one golden rule is that regardless of what game mode you play, at the end of the day the main reason gw2 does anything is because it has to make a profit first. That being said the majority of their profits are pve related, and it's where their effort has been, it's no secret. But with pvp, there's not many people working on it in terms of numbers, balance patches are wide spread and underwhelming, and the population of pvp is so low that regardless of how look at the matchmaking for better or worse, the quality of matches will be arguably poor. Something needs to be done. So my suggestion is what if you made heart of the mists free, as a makeshift glorified trial. Players would get access to every expansion in terms of talent specializations that everyone else does so there's a equal playing field, and you can stay there permanently if you'd like to, but if you'd like to go outside the heart of the mists, then you'd obviously need to buy the expansions to do so.
Sure on the flip side you could make an argument that arena net would lose money from people that just play pvp. While that's true, however what they could gain from potential new players would outweigh the cost of making heart of the mists a permanent free trial.
TLDR "ish": Heart of the mists goes free to play, new players try it and buy the pve portion of the game to experience the rest, not to mention gemstore items. They take that money and invest it back into pvp because it's essentially the face of the game when it comes to whether or not new players stick around. Everyone wins.