Except they just renamed iOS for iPad as iPadOS this year. If they were to rebrand iDevices, they would have called it padOS or tabletOS instead.
Maybe. But names can be changed...again. Now if this is the direction they're going, they're doing it carefully, incrementally and strategically.
It's not at all hard to imagine the following future:
Phone / phoneOS
Watch / watchOS
Pad / padOS
TV / tvOS
Mac, Mac Pro, MacBook, MacBook Pro / macOS
They've already done 5 of those 10* items.
*Counting the Mac naming as one branding move.
This doesn't even count:
Music
TV+
Arcade
Card
I've said it before and will say it again, this move might be a very good one for Apple because it puts Apple at the center of the naming and branding and opens a wide variety of more generically name devices that still fit within the Apple brand portfolio:
Tag
Glasses
GameController (ugh)
But you get the point.
And while article does not say this is what Apple is doing with iPhone, the idea of dropping "iPhone" from the back is exactly the kind of subtle way Apple might do this.
Heck I could even imagine them not mentioning it at all, just sort of casually announcing:
Phone 11
Phone 11 Pro
Phone 11 Pro+
Something like that.