Looks like Foursquare has no immediate plans to revamp its Foursqaure app in Windows Phone Store. Recently, Foursquare split their apps into two, Swarm and Foursquare. Swarm will focus on check-ins, leaderboards, and more while Foursqaure will turn into a local exploration app. While, Swarm app is already in Windows Phone Store, Foursqaure app is yet to be updated.
Today, Foursquare app for Windows Phone 8 has indeed been updated to version 18.104.22.168.
Unfortunately, this is just a minor update with support for addition display resolutions.
Find the app in the Windows Phone Store here.