In Pokémon Go are eggs predetermined before you hatch them? What I mean is, has it already been decided what you are going to get from that egg before it’s been hatched? Or is it a random selection during the hatching?
Yes, they are already predetermined (experience and research from thousands of players over at the subreddit /r/pokemongo).
This is so, because no matter at what level you are right now, the Pokémon that hatches is limited by the level you were when you got that egg.
You are level 10 and get an egg.
Now at level 20 you decide to hatch it.
It will be as strong as limited by level 10 and not level 20, because it’s already predetermined (like in the original Pokémon games)