Still present in High Sierra. Can't believe they supported it for so long. I think that's the only major API that hasn't really changed since Leopard which means all apps that built with Carbon are compatible with every macOS since Leopard. At one hand, it's a good thing that people can use these apps even on the very old hardware that can't run newer versions of macOS. But on the other hand, the API is so old that it doesn't support any of the new technologies in macOS like Grand Central Dispatch, 64-bit, HiDPI, App Nap... I personally can't wait for Apple to remove this API entirely so developers can finally start thinking of transitioning their apps to Cocoa