First of all, no links to any hacks in this thread !
It can be assumed that given a big enough player pool and popularity of the game, if hacks are possible, they will become available.
The basic concept behind whether or not hacks are possible directly depends on how much of the gameplay is server side and how much of it is client side.
Having as many actions as possible being made/controlled/calculated on the client side considerably lowers server burden and from the business perspective is a lot cheaper. After looking into it, it didn't come as a huge surprise, that in Guild Wars 2 most of the gameplay is indeed clientside. Since Guild Wars 2 doesn't employ a subscription based business model it's understandable that they would try to minimize maintenance costs postrelease.
What does this mean for the players ?
For example, player positions aren't a server kept secret, they're clientside - means wallhack is possible once client is cracked
Player movement and movement speed isn't serverside - speedhack is possible (actually already available), this also makes a teleport hack technically possible
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Added:
There's a GW2 speedhack already available that lets you add a percentage of your choosing to your movespeed (obv not gonna link it)
So you can add 15% and move slightly faster than everyone else, but noone else would probably even suspect anything.