Bannan and Clark will make it, I even think they'll both end up at somewhere like Man Utd. As for Herd. He'll get found out to be average, like Hogg was/is.
His decision making is suspect. Dives in for tackles when he should stay on his feet, shoots when passing would be the better option, tries to take a man on when there is no space etc.These are things that can improve with coaching and experience so I wouldn't write him off just yet.
I may be alone, but I actually think he's looked bright most of the times he's come on this season. Provided a quality assist at Everton for instance.