I don't think AI is going to be as easy to give up on as nuclear. Nuclear has some long term/diffuse benefits, but in the short run it's just one among many types of electricity generation. AI is a whole category, not one substitutable member of an already common category. Us giving up on AI development would be more like giving up on electricity generation than like giving up on nuclear.

Human cloning is a solution with no corresponding problem. We can make more humans very easily, if we have someone willing to bear those humans and take care of them.

If AI becomes demonstrably useful, opting out will be incredibly challenging, since we cannot force other countries to disarm.