Wow, I'm glad I stumbled into this before clicking on the next iPhone update to iOS 11 due in the next few days.
It seems that 32-bit apps won't work in the new version. I have a number of apps I use regularly which haven't been updated to 64-bit due to the developer being taken over, and I'll lose access them if I update to iOS 11. In fact, I'm not even sure I'll be able to reinstall them if I lose them or have to reset my phone.
Just posting this so others are aware - check for 32-bit apps by going to Settings --> General --> About --> Applications which will list the 32-bit apps if you have any installed.



