There's still a massive Garlean Flagship sticking out of The Nail in Coerthas. But i'm hoping Dzemael Darkhold that's underneath it will lead up there someday with a (Hard) mode restyle.

Same for the wreckage at the middle of the lake of Mor Dhona.

Also looking west from Camp Tranquill, to the side of where The Lost City of Amdapor's supposed entrance is, there's a huge reach of cliffs and mountains that have large jagged edges sticking out of it. A perfect badlands enviroment to explore with no way to get there.

And lets not forget the closed off Garlean Fortress in the East Shroud. You can look over the gates, but you cant get close.