Earlier quoted context omitted.
I think Apple will ultimately destroy the data center, I hope they succeed.
Maybe for compute, but not for storage. Why can’t I backup an iOS device to a local NAS in the way I can use Time Machine, for example? (Rhetorical question; the answer is obviously that they want to sell more iCloud storage for that all-important services revenue).
You can backup your iPhone using Finder.
Finder -> Locations -> Your iPhone -> Backup all the data on this iPhone to your Mac.
Once you have done this you can find the backup in "Manage Backups", right click on an entry and select "Show in Finder". From there you can copy it to your NAS.
Not as smooth as a Time Machine backup but it is possible.