Now i am not talking about the fact that i want Cantha back as soon as possible.
I am raising the question on how it would work and what would be the accompanied szenarios that would occour, if this continent would be reintegrated into the accessable lands.
First off, the last things we know about Cantha that it is a monarchy, akin to the old chinese ways. The whole Cantha area had this chinese, asia, suburban style.
In the last story update the new leader cast out all non-human races in a great war, sealing of the lands to any who try to get in. That is the reason why the canthan Tengu came to Tyria and build the Dominion of Wind.
With Zaithan presumably dead, we now have theoretical access to the waterways to Cantha (if the DPS does not show up, though that would make thing interesting), so the people of Tyria could ask for help there.
The problem here lies within the nature of the politics. A group consisting of all races, against a only human group.
This is bound to create conflict.
It does not matter which group goes over there to negotiate, it is bound to have races other then human in it. Be it Lions Arch or the Pact. They all consist of members of different races.
A sole human advance would not work in the multi-racial story telling a-net is going for.
Let`s go with the idea of the Pact approaching the Cantha boarders with their ship/airship.
By going there they could be attacked up front or beeing allowed to speak, with varying success, depending on how much has changed.
Either way, i do not think that going there we get welcomed with open arms.
An attack o war with Cantha would not benefit, so we either have to give up on that front, or we have to find a way to get our voice heard.
For that we need to go into the lands first, but how? The Order of Whipsers might know a way. They were traveling in secret for hundreds of years, were even able to bridge the crystal desert between tyria and elona. They might have a way to sneak fellow pact member in.
From here on we can find out what is going on in that unknown land. Are the people happy with the regime, what has changed over 250 years. Is there a way to give us some leverage?
We do not know how Cantha has changed. What their problems are and how our existens would effect them if any.
There exists some artwork which shows a rather advanced asian style cityscape, people associated with cantha, since it was by the artist who did most of the GW2 designs.
To be honest, aside from the fact that cantha is there and it is xenophobic we do not have much information so far. However, what would be your lore based ideas to get it back into play.
Maybe even involving a long arc like i am sugesting here.