Apple announced the next major update to iOS at WWDC 2017 today, calling it, you guessed it, iOS 11. Three devices will lose support, making the OS exclusive to 64-bit devices, and while the company didn't explicitly say so during its keynote, 64-bit apps.
The first Developer Betas are out, and 32-bit apps are not supported. It won't be coming back either, as the release notes explicitly say that the apps won't run on future versions.
Developers that want to target 32-bit devices can still do so. They'll just need to target those apps for iOS 10, and of course they'll need to include a 64-bit build with the submission.
If you're using the new beta, there are some known issues that you'll notice. If you select 'Learn More' from a message such as the one on the right, nothing will happen. Also, if you attempt to sync a 32-bit app through iTunes, it will only leave a placeholder.
The move shouldn't come as a surprise to anyone that frequently uses 32-bit apps. When Apple released iOS 10.3, launching said apps would display an error message saying that a future version of the OS would no longer support them. While it was speculated at the time that the 'future version' would be iOS 11, we can now confirm that this is indeed the case.