Ask HN: For how long will CAPTCHAs exist?

I think most people here on HN agree that computers will surpass human intelligence at some point int the future. Kurzweil prediction is the year 2029. Personally I tend to thing its a bit later. Maybe 2050. But how long before that will CAPTCHAs become meaningless? Will they hold up right until the point where computers surpass humans? Or will they fall sooner. And what will happen, that "day"? Will anything break?