The iPhone was a completely post-Mac product; now Apple needs a post-iPhone product, and they don't seem to know exactly what that could be. They are swinging wildly at fashionable fads from competitors (watches after Samsung, pro tablets after MS, cars after Tesla, etc etc), with little end result. But Apple is at its best when it disrupts mediocre and stalling markets (grey PCs, crappy mp3 players, stupid phones), not running after fashionable fads. They should leave "fire and motion" to the rabble and come up with new panzer designs instead.
I think tablets have reached market maturity surprisingly fast. At some point it has to become more about profitability, ecosystem strength and market dominance than growth.
Is the iPad Pro a big improvement on that?