At least by our very large company's metrics we have gone off the charts on productivity because people are working more hour from home. Plain and simple.
The myth about spontaneous interactions has to stop. I call those distractions and time wasters. If I need to collaborate with someone, texting or a video chat with shared screens more than gets the job done.
Outsourced the costs? I house sits empty all day when nobody is here. Sure there is a slight increase in utilities and such but are way overshadowed by the money we save in not commuting and not eating out every day.
Then the outsourcing our jobs canard. If it was so easy to do that, we'd all lose our jobs overnight. It's not easy. The talent pool isn't big enough and especially for foreign workers, the tech talents aren't up to western standards. That's not going to change for along time if at all.