Just like you've said, IGG stepped in way too late (as in, at least 2 years late) to stop all this duping nonsense. Moreover, unless IGG somehow finds a way to stop each and every known form of duping, just stopping the current duping situation won't count much since people can, and will, just find another way to dupe stuff.
Like some others suggested, rollbacks will be a decent idea though as the saying goes...prevention is better than cure, no? Again, just rollback is not gonna be enough since as mentioned earlier, people will find a new way to dupe. With that, the whole process might as well repeat itself until IGG decides to shut down the game for good.
Call me pessimistic, but I do think it's wise to not rejoice over IGG handling the situation for now since we're not exactly out of the storm yet unless the duping is guaranteed to not happen anymore. Honestly, thinking that the duping is over for good sounds like wishful thinking.
After all's that said though, I will definitely NOT be coming back to WLO whatever the (current) situation of duping may be. For one, I've pretty much had other interests and commitments already which supersedes WLO and even then I had already started to lose some interest in WLO since friends I used to play with quit the game within the last few months of me playing WLO.
Edit: To those who are hoping that IGG will introduce new updates to this game after their actions regarding the duping incident, don't get your hopes up too high.