Looking at https://forums.macrumors.com/threads/ios-11-developer-beta-app-compatibility.2048556/ there are many apps beside 32-bit ones that won't run under ios11. I rely on several older apps and some developers have already told me they don't intend to update them to be compatible with ios11. So I am wondering if I will be able to keep running ios10 on my iPhone and iPad and not be forced to update to ios11 in order to obtain security updates. After all, there must be many older models of iPhone in use that won't run ios11. This is the first time I am reluctant to embrace a major iOS update but with OSX/macOS on Macs I have sometimes delayed and Apple has continued to support the old OS with security updates.