Krebs looked pretty great at the world's last summer, so I don't think the ceiling is the issue.
Hockey IQ is really about reading the ice. Decision making with the puck and hockey IQ are not the same thing. Low hockey IQ players can make the smart, simple play with the puck regularly, that does not mean they have high hockey IQ - and vice versa.
Krebs has a high hockey IQ, he sees the ice and his teammates well(hockey IQ), he just makes poor decisions with the puck (not hockey IQ, the decision making is more a common sense issue here.) - learning that something that worked well in junior and well on the big international ice does not work in the NHL, and not continually trying to force it to "work".... That is more about common sense than hockey IQ.
Learning what you can and can't get away with in the NHL is more about experience and not hockey IQ, but the lessons are not really sticking with Krebs for some reason. But he's still only 22, and has been getting his head punched a lot the past season, so maybe this is going to take a bit longer than normal....
It's fine if you want to move on, but I strongly believe he has a lot more growth to show at this level, and I think he may be one of those players that will eventually just one day in the foreseeable future "get it" and be a valuable asset.
The push to rush all these teenagers into the NHL on this board is mind boggling given the recent history of this team. Let the kids percolate and be patient with the Krebs and the Mitts and the Jokers in the cap era NHL and see what you got before cutting bait.