I'd be pretty surprised if Krug waived his NTC for Columbus.
However, I don't think that it is the least likely of destinations and I think there is a decent chance that Columbus won't be on his 15 team no trade list next summer. Other than Detroit, Columbus is the closest NHL city to his home town and Ohio has a lower tax rate than most of the league (the exceptions are the no-tax states and Pens/Flyers). As it stands right now, he'd be the #2 LHD on their depth chart for 2025/26 (that could change if they extend Provorov). Barring the perpetual on-ice mediocrity, Columbus is a decent spot for him to end up in 2025 when he has to leave about half the league available.
But I think that he'd much rather delay going there a year than waiving for them right now unless things get really contentious here. Any Laine trade we made would get heavily scrutinized by the league and PA if we waived Krug and Columbus claimed him.