Some would argue that iPad Pro is 90-percent there already. Lewis Wallace:
Even with all the new productivity features in iPadOS, the iPad still can’t touch the Mac when it comes to ease of use. The reason? It’s complicated.
Of course. But that wasn’t the premise. Why never? I think it’s the imprecise interface and the lack of powerful applications that can do– on a Mac– that which cannot easily be done on an iPad; even with a keyboard and a mouse.