Has anyone else noticed that if the Apple Watch version of an app is removed from the App Store it also disappears from your Apple Watch. It's happened to me with the eBay and Google Maps apps. I had both on my Apple Watch and they've both disappeared from the Apple Watch and the app listings no longer say there's an Apple Watch version of the app.
It makes sense. If the main iPhone app no longer supports an Apple Watch app, then the orphaned app on the watch wouldn't work anyway. So, once the iPhone app updates, the watch app should go. Otherwise it's just taking up space, and irritating people when it doesn't work. And the automatic mechanism to update/remove the watch app has to be in place; otherwise your watch apps would never get updates.
Here's an amplification of my earlier post. With an iOS device if you have an app on that device that's later removed from the App Store the app in question remains on your device and will still be operational if it's a stand alone app or the developer has not shut down online support. It's different on the Apple Watch. If an Apple Watch app is removed from the App Store, the next time you sync it with the Apple Watch app on your iPhone or switch between paired Apple Watches, the app will be removed from your Apple Watch. There's no library of Apple Watch apps stored on your iPhone that can be synced to your Apple Watch even if they've been removed from the App Store as can be done with an iOS device.