I don't know... Watching the array of Apple OS'es (OSX , iOS, WatchOS) during the WWDC keynote, I got the sense that this has got to be a maintenance nightmare. Microsoft seems to be aiming another direction with the one Windows theme--although the thought of making that work also makes me cringe. I'm out of touch with modern development, but simple seems to me to be the best policy.

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?