How long would it take to...
Blockade of ships off the coast of Claw Island? If such a thing existed, ships to Southsun Cove wouldn’t have been possible.
You’re likely referring to the ships on the world map – sadly, this is a map image that’s stuck in time, and shows the ships that are there for the Battle of Claw Island (the ships are no longer there during Retribution, I believe, and certainly not there after).
If any blockade of Risen ships still exist, it’d likely be between Orr and the Ring of Fire – at the Strait of Malchor.
But how long would it take to remove Orr’s corruption and the remaining risen? Really, as long until Anet says so. But even then, should such happen… why would Tyrians go to Cantha, whom kicked everyone out? There’d be no reason to go to Cantha until Anet gives a plot reason – which they won’t soon at least.
Stop treating GW2 as a single story. Each Season and expansion should be their own story.
Shipping occurs between LA and Rata Sum as far as I know.
As for those ships, IIRC they are from the second mission at claw island, where they have an entire fleet of lionguard ships fighting the undead navy around the island as the player clears it.
As for Orr, it’ll take a long, long time. Not only to clear the risen, but to let the cleansed waters wash out all the corruption and fully flow throughout the lands. Decades for the corrupted water to be washed away maybe, and even after that a long while till it’s fully capable of being livable.
Since Tequatl’s extra gain of power and the change in risen (lower density, but more powerful), it’s expectable that the source of risen isn’t removed.