The issue with this idea is that it makes consumers feel like they can use one device instead of two, while decreasing the need for iCloud and custom Mac and iOS accessories. Right now we have three core devices to monitor for updates: iPad, iPhone, and Mac. As much as we make fun of their lack of intrest in the Mac It is still a key product and they do want us to buy new ones. They solved the issue with PC's not making much return by avoiding cutting edge components (except the iMac Pro which includes a 3x markup).
I have been half joking that with friends that our iPhone should be our computer and the iPad and Macbook/iMac/Display/Apple TV should all be smart devices we can use the iPhone with. Just like there is a custom UI for CarPlay, there would be a custom UI for each of these. We thought the iPhone would bring more attention the Mac, but the opposite occured. The iPhone is the key revenue for Apple, and everything else is an accessory for ecosystem. Universal Mac Apps support this idea. The problem with my idea is that while it makes it a lot easier to get into the Apple Ecosystem it isn't as sticky as having three $1000k+ devices in your home.