Foursquare’s Dennis Crowley Can’t Stop Believing
medium.com
medium.com
Foursquare has a lot of data. As a bonus, they've also realised that the company is very likely viable just living off other people wanting that data. If they can use that data well, I wouldn't be surprised if Foursquare turns into a serious competitor for Yelp (or even TripAdvisor, etc). If anyone wanted to try and usurp Yelp, it'll be Foursquare, not Facebook or Google or Apple.
Route requests probably aren't that interesting to someone trying to supplant Yelp - if you were trying to supplant TripAdvisor you might want travel bookings, but that's a case of connecting to the users email account (with their permission) and grabbing the lovely JSON encoded tickets and booking details.
On the other hand, Google and Apple don't need you to install anything additionally on your phone and they know where you are and when you're there.