[saagarjha]

When Apple removes an app from the App Store, you cannot download it anymore but it will continue to run on your device if you had it already. Apple also has the power to "blacklist" applications and prevent them from running on your device even if you've installed them (https://iphone-services.apple.com/clbl/unauthorizedApps), but this list looks empty for now. Usually what happens in the latter case is that the violation is so egregious that they will instead terminate the developer's Apple Developer account, which will have the same effect.