We’re looking to bump our minimum version target to 16. If we were to release one final iOS 15 version of our app with a bunch of bug fixes, will users be able to download that version in the future after we bump to iOS 16?
Or will they just be cut off from downloading our app entirely?
Users on iOS 15 will still be able to download your 'final iOS 15' app version if you let them via last compatible version. You can look at this page and see a screenshot of it in App Store Connect.
Keep in mind any services or APIs that you integrate with are still subject to availability per those providers.