Heart of the Mists > Lion's Arch???
Since it’s not really an intended feature, and more just a side effect of the system, I doubt it would be implemented. They want you to sink money into waypoint costs, so making it easier to get around them probably won’t happen.
In fact, what I might see happening is actually them making WvW like leaving the Heart of the Mists, where it puts you back where you were, to shut this down.
It’s not a terrible idea, I just doubt it will ever get used.
Also, I doubt it would ease that much server traffic in LA. Most people stand around Trader’s Forum/BLTP. The people porting around the map either get in and get out quickly or stay, so reducing their loading screens isn’t really going to help all that much.