I'm working with a company that has a couple of apps on the app store. They are concerned that with this April 2020 requirement that their apps will be non-functional or removed from the app store unless we update using the new SDK and requirements. We have the apps working on all iOS 13 devices, and have no updates to currently apply to them. Do we *need* to update using the new iOS 13 SDK or are the apps okay to exist without updates?
My understanding is that you are not required to update the apps if you don't need to, what you will be required is to build with iOS 13 starting April 2020 for next submissions. If the current versions on the store are working fine on iOS 13 devices, then you should be fine.
This has nothing to do with existing apps already in the store at that date. It only applies to new or updated apps. Apps already in the store won't go dark overnite.
As always, common sense says take Apple's lead to heart, don't wait to find out later and you should already be testing to be sure you're a good citizen, and your users don't end up testing for you.