We have mechanical muscles, and the human strength that was needed before the industrial revolution is no longer important; weight lifters still strength train, but it's a hobby, and nobody needs to do it.
We're building mechanical brains, and the human thought that was needed before the intelligence revolution is no longer important; some people may still study, but it'll be a hobby, and the people who participate in the intelligence revolution (rather than being crushed by it) will no longer need to think.