It will be interesting what Apple decide to do in the medium to longer term.
Any manufacturer generally does not want to deliberately choose to limit their own potential market.
At the moment, as the watch is mostly an almost dumb terminal screen for the iPhone, it makes perfect sense that it's done this way.
It's simply an iPhone accessory and nothing more.
As years and model go by, Apple are able to break the umbilical cord, and the Apple watch can grow up into it's own independent device, which I'm sure it will, then this may change.
With Android having more market share than iOS around the world, and in some counties, iOS having almost no real market share, Apple, in time will either have to do this, or lose these markets to competing devices as you can be sure, other watch brands are not going to sit still.
There will be other Smart Watches that will work across multiple formats, in competition with the Apple watch that only works as an iPhone accessory.
I'd say it's pretty obvious that Apple knows this is not the best scenario for the longer term.
Perhaps it will take say 2 to 3 years for this to change?
I'm sure it will, eventually as it would be silly otherwise.
At the moment, Apple's only market is a percentage of iPhone users with modern, and that's it.
They can't sell the watch to anyone else.
I think we can all see, that's not a sales tactic you would wish to keep for the long term.
Unless of course, Apple are currently arrogant enough to feel their watch will always be so amazing, and so much better than anyone else's that people will all flock from Android mobile to iPhones, simply so they can also have an Apple watch.