Theoretically, you are right. But SMBs have heard of Foursquare and this is invaluable for them as this is how they are going to make money in the end. As for consumers - you are right for the single digit millions who check in from time to time, but for others? Foursquare is an app that was not for them, but they know it was about local and they did not mind it. The hard part is going to convince them that this new app is more interesting and better than Yelp, Sosh or others.

Anecdotally I've actually had to explain to multiple people that they should use Foursquare (I find the discoverability features actually excellent) - and been met by the "but that's the check-in app" response.

The number of active people checking in is certainly low, but general mass-market awareness of their (former?) line of business is quite high.

So on top of convincing people your discoverability features are great, you have to first convince them that your app isn't what they already think it is. Personally I think this is very poor branding.

Where did you find that the check-in rate is low? The only numbers I could find state that it's in the millions per day.

Millions compared to what? Their historical peak check-in rate? Number of active users? Number of total users?

Everything I've seen anecdotally points to Foursquare having a small core of highly active users (people who check in multiple times a day), with a very, very, very long tail of infrequent/never users.

I have no inside information on this, but I'm also willing to bet that their current daily check-in rate is lower than what it was at their peak. The whole checkin phenomenon came and went, and while it's not gone entirely, it's simply no longer relevant to the mass market. "Millions" of checkins a day is, frankly, very low for a consumer tech product that has existed for 5 years and taken $160mm in funding.