I got this popup when I went to the app (I updated to iOS 10.1 yesterday.) Is a new app inbound, or should I just remove the current toucharcade app?
No new app is on the horizon, it won't get approved by Apple. It also isn't realistically slowing down your phone, as the TouchArcade app was built for iOS 6 and to run on the iPhone 3G. Any performance hit caused by the app not being 64bit is completely negated by modern iPhones being exponentially more powerful than the original hardware it was developed for.
http://toucharcade.com/2016/10/26/the-toucharcade-app-and-the-ios-10-1-may-slow-down-your-phone-popup/
They've finally started trying to kill it. Blast it all, we're going along fine without their attention.
