Agreed, this will be the way forward in the future. I've already seen one of my apps (Authy) say "We're no longer building a macOS version, just install the iPad app on your mac".

That's great, but you need an M series chip in your mac for that to work so backwords compatibility only goes back a few years at this point, which is fine for corporate upgrade cycles but might be a bit short for consumers at this time. But it will be fine in the future.