Several clues in the beta of iOS 10.3 suggest that Apple will soon abandon support for 32-bit devices, such as the iPhone 5. Many thought that Apple would skip the pace and only support 64-bit devices with IOS 11. However, it seems that the manufacturer has decided to do it rather.
Last night, Apple proposed the first beta of iOS 10.3.2. When visiting the developer portal, it is possible to download the beta version for all 64-bit devices, but not for 32-bit devices. The iPhone 5 and the iPhone 5c are absent for example, just like the iPad 4th generation. They use a 32-bit architecture with the A6 processor (A6X for the iPad). Apple is upgraded to 64-bit with the A7 processor, used in the iPhone 5s.
There are two possibilities. Either Apple has decided to completely abandon the 32-bit devices and these will have iOS 10.3 as the ultimate update. Apple either has everything planned or intends to propose the support of the 32 bits with the next beta of iOS 10.3.2. The manufacturer saying nothing about the subject so far, it is difficult to know which of the possibilities is the right one.