I really don't believe AI will cost us our intelligence or bodily functions. Evolution don't take place in a day, it takes years. If man had evolved, that means we needed to change from a state where we were lower than what we are now. Machines will never take over. And if AI mean another evolution, then I believe the next evolving set of humans will be supper and harness more of the ability we can not use now.
It shouldn't be a bad thing. If the Java man living in the cave could evolve to this present age man living in houses, there should not be a cause for alarm.