I think Krugman has generally focused on labor productivity when talking about technology and the economy. He made that prediction in the 90s, when the productivity paradox was a topic.

Obviously I was wrong about the internet petering out, and have admitted that. So it goes. Show me an economist who claims never to have made a bad prediction, and I’ll show you someone who’s either dishonest or unwilling to take intellectual risks.

He has a recent-ish oped (direct nyt link) where he admits he was wrong but then brings up labor productivity again, waggles his eyebrows, and gives you a smouldering look. He sounded convincing to me, but I don't have the background knowledge to know if he's cherry picking his numbers.