Having read this I'm substantially more convinced that Dennis Crowley knows what he's doing. The only bit Foursquare has really messed up was the split into two apps, but it's not something that they can't fix. Swarm being an app that feeds data into the main Foursquare app is a hard setup to make work (users might use one or the other, and not both), but Facebook has made it work with Messenger and the main Facebook app.
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.