I am a little concerned with this. I have 3 of their synths. I am away from home right now but did log into Korg Usernet and I was told that I have to migrate as well.
Do you get new licenses? My main audio machine is off the net and all the Korg stuff works perfectly for me. But once in awhile I have had to re-authorise something and I guess that will be the time I will get into trouble.
I think it is worth the trouble because they do sound incredible. Wavestation especially. It may be an old machine but still holds up even today against anything really.