I think CarPlay is a test of this use. It's really similar, in that you connect your device to your car, and apps render a different view on a different form factor. You have a certification process so you know you have at least a chance of a good user experience. It's a subset of device functionality, instead of supporting more functionality.

If Apple invests in enhancing CarPlay, it might be a sign that they are scaling to a wider convergence market. If they don't invest or abandon it, then maybe convergence won't happen. They're famous for saying they're not working on projects that they are actually working on, so we have to read between the lines.

After upgrading from an iPhone 6 to an iPhone XR, I've been thinking how close the latest gen devices are to traditional computers anyway. The configuration/settings and features are so far beyond the first gen devices that I think convergence will happen, nobody knows what it will look like yet.