Bapabooiee: Not going to happen, because then that'd mean that GOG's games would have to be tied into the GOG service somehow
Not necessarily. The achievements could be optional, just like cloud saves.
But I personally prefer GOG would continue to keep things as simple as possible, and I am sure there are other things for which they could use their time more productively. Also, I feel that even if GOG offered an achievements system, people who like achievements would still bitch because they are not _Steam_ achievements.
All that said, I prefer ingame achievements, which reward you somehow inside the game for doing the extra mile. The example I like to use is how in GTA3 you got some kickass weapon (very usable e.g. for the end fight) if you found all the "packages" scattered around the city.
I need no stinking badges, I want the game reward me somehow inside the game for doing extra stuff. And I want them to be somehow meaningful, the "external" achievements tend to be rather artificial.