The market for tablets is pretty much saturated, and the market for smartphones is no longer expanding at a breakneck rate. Laptops/desktops are not a growth segment, so Apple doesn't have huge potential for growth anymore unless they can find a new and very profitable product segment.
Apple isn't even really trying in any kind of serious way in the enterprise market, and their cloud efforts are only focused on supporting iOS for the most part. So where Microsoft (and Amazon) is poised for strong growth, Apple isn't even on the playing field.
I think back when the iPad 1 and 2 was gaining traction and getting businesses excited about tablets, is when Apple should've made a big push into enterprise. I think a lot of orgs (particularly gov't and hospitals) would've changed to being Mac shops if Apple offered the server, productivity, and desktop/device admin tools enterprise needs. But they largely ignored that opportunity and now the window is all but closed.
I know Apple's philosophy was to have a laser focus on what they do well, which was consumer hardware and software. But I think they had/have more than enough money to be a strong player in the enterprise market. What could have been.