According to Foursquare's co-founder Dennis Crowley, as quoted by TechCrunch, the service saw 5 million checkins per day as of Feb. 2013. But that was the same as per-day checkins as the previous year. Flat growth to me, especially in their space.

The rest, and a fairly critical piece of my statement, about checkins moving to Facebook and Path I admit wholeheartedly was anecdotal and speculative.

http://techcrunch.com/2013/04/11/foursquares-new-series-d-ro...

http://techcrunch.com/2013/03/16/interview-dennis-crowley-of...