I didn't mean done in the sense of they'll never do anything again. But given how long it's been since this game came out, it seems to me that the argument for implementing the achievements properly gets weaker as time goes on (why invest the time when the game's biggest financial impact for CDR is already past). Even if they did make a return to the Witcher series, I think they would be focused on the new game(s), not fixing old ones.
Sure, a lot of game companies patch their games 3 times then never touch them again, but a lot of companies support their games for several years if not continuously too. It's not as common but it happens, and CDPR is one of the companies that seems to value their gamers and go that extra mile to do things. Look at Valve - they still actively support every game they've ever released including putting out regular patches for Half-life released in like 1997. Why would a company do that? Because they obviously think that there is value in doing so and they decide to do it.