I'm not convinced he was that good today. I feel like if a rider is the strongest in the race and out of position due to crashes or mechanicals you can see how they push their group forward once they take a turn. Roglic never did that. Maybe he burnt too many matches in the phase right after the mechanical but considering the situation he was in he actually didn't end up spending that much time in the wind.
The thing is, I'm saying all of that and I still don't feel like he has to be particularly worried, because his supposed main rival Ayuso looked argubly even less convincing then him. There was a moment on the third sterrato section when I think Ayuso thought, this is how far his team got him, now it's time to blow up the race and have the best gc riders around him fight it out in a TTT against the gc riders around Roglic. And he just couldn't blow it up. Meanwhile Ayuso's team had 4 riders in the groups in front of Roglic and somehow couldn't create a proper gap against a group that was mostly led by Giulio Pelizzari.
I think, if his shape in the third week is on point, he should still have everyone under control except the big wildcard Del Toro. He's the one guy who might simply be out of reach now if today was an indication of how well he'll do in the high mountain stages, but I would be surprised if the 21 year old doesn't run into some trouble along the way.