That only matters if you are using 32-bit software. Deleting the 32-bit software is not somehow a benefit with relation to that goal. You are saying that it is better to run all 64-bit software. I am arguing that there is essentially no benefit to a device that is incapable of running 32-bit software when it clearly still has the hardware.
I'm saying that supporting multiple ABIs has a nonnegligible cost, regardless of whether the hardware supports it or not. On my MacBook (I haven't touched an iOS device in the last 5 years), the 32-bit dyld_shared_cache is 300 MB, and the 64-bit one is over 600. There might be baked in assets that are larger on the laptop form factor, and libraries that don't exist on the phone, and demand paging might buy you some of that back, but it's still going to be an absolutely massive chunk of code.
I'm not actually arguing that this is a net win for the consumer of the device. If your choice is between a device that supports 32-bit and a device that doesn't, with literally zero difference in performance, I would totally agree with you (modulo engineering effort it takes to maintain them all, but that probably isn't too high). I'm just saying that there are real quantifiable benefits to what they're doing.
edit: and that's not considering the actual advantages of forcing 64-bit like improved security via better ASLR
What you say is true, but can you imagine trying to explain to the average user that the reason their phone is running slower than necessary is because they are using applications which necessitate multiple libraries be loaded simultaneously?
From Apples perspective, the App market is so saturated that any missing functionality will be quickly replaced. This way, everyone gets a performant system without needing to know what the difference between a 32bit app and 64bit app is.
I think you're assuming the upcoming A11 chip will also be capable of running 32-bit software. The hardware may be changed, for the sake of simplicity.
As far as anyone is reporting, Apple is intending to remove support for existing devices that get updated to new versions of the firmware, not just for new hardware.
