A quote from someone about two months back regarding a thread about yak slapper and a few other achievements:
“We are actively working on addressing this. It takes more time than you might think, however, because we also have to make sure to have a solution that doesn’t mess up people who have achieved titles already.”
Honestly, with so many months gone by, I expected it to be in with the achievement rework/remodel. But it’s not. Has Anet decided that killing 1 million yaks is achievable? It’s not like its physically possible for anyone to be even remotely close to completing this achievement for at least another 8 years and only if its the only thing they do in the game and the only thing they have done since launch. And if so, they get 25 achievement points.