The vast majority would almost certainly remain on the app store, and practically nothing would change for those apps in terms of security or convenience. Android has allowed downloads from other app stores for years, and not once has it posed a significant issue. Epic isn’t trying to force apps off the app store. They are only trying to open up options for other developers to distribute and make money without having to give it all to the monopoly that is Apple. This would give users the option to also move outside of the walled garden, but at no point would anyone be forced to do anything.