This might be one of the reasons they're transitioning to Apple Silicon, as it will allow them to justify the raising R&D costs over a wider array of products.
While 10% is small in relative terms, it's still huge in absolute terms. And the Mac also remains an important nexus for Apple's wider ecosystem, even if a significant majority of their customers will never own one. Because of the way Apple technology is developed, and by virtue of being largely untethered and unmanaged, Mac is the bootstrap platform for everything else Apple does. It doesn't always have to be so, but I don't see Apple releasing anything else which could take its place.
