Why Apple Should Kill Off the Mac
on.wsj.com
on.wsj.com
I think it is clear that the author is not a developer.
Is anybody out there more in touch with the details--Is there enough significant overlap that keeping the ecosystem in sync with itself seems to be a reasonable task?
So from a programmatic standpoint, they are three platforms with one foundation. And Apple isn't going to proclaim "one OS X" any time soon since they want to emphasize (and make sure developers are aware of) each platforms' differences: iOS for touch interactions and limited multitasking, watchOS for limited interactions (glances), OS X for power users and doing things not possible/practical on iOS. But all three are programmed with Objective-C/Swift and use some Cocoa-like framework.