When you are evaluating a litter of puppies, is there some way to tell if a puppy will eventually carry his tail too high?

Little puppies carry their tail high normally. Tails that are carried higher than 80-90 degrees angle, and over the back will probably be too high.
Dominant puppies will carry the tail high. It does not have to do with the tail set. JMO

You should be able to identify a high "tailset" when you evaluate a puppy at 6-8 weeks. I think you are referring to a high "tail carriage" which is different, a puppy can have a good tailset but still have a high tail carriage. High tails can run in lines, and be inherited. I've seen puppies who I was certain would have high tails that I saw at an older age and carried their tail straight off the back, and others who did not carry their tails high when they were very young end up with high tails when they got older. It can be hard to predict. I was told from someone very knowledgeable that it takes 3 generations to totally breed it out of a line.

My boy carried his tail high (straight up and almost over the back) at 8 weeks. I don't have a single good photo of him on the table because of this.
He is now just over 2, a finished champion, and has carried his tail straight off his back since about 4 months of age