This is a good thought experiment, and I have a related one: Imagine you are sitting in a stadium full of your ancestors. You're at field level, beside you is your mom, beside her in your grandpa, beside him your great-grandma, and on until the stadium is full. Somewhere near the top is your great^100,000 parent, some kind of australopithecus ape-like creature. Where in this stadium will you draw the line and say "this is a person, sentient, conscious, deserving of legal rights, but the parent sitting next to them is an animal"

It's impossible to draw such a sharp line, because the boundaries of consciousness are extremely fuzzy. We should expect the same fuzzyness of AI and this period will likely last many generations of AI.