Apple's history of being walled garden is interesting.
So in the 80s and 90s, Apple tried the wall garden approach. And it absolutely failed. The IBM clones won out, with software and all that that worked across vendors and platforms. The hardware and software could be separated, so Apple's approach of both and closed didn't work.
Then Apple languished for decades.
Then with smartphones you had this product where the hardware and software needed to be tightly integrated. And tight integration was necessary to give a high functioning, small, compact device, where you needed the software to be highly optimized for the specific hardware.
I find it fascinating that Apple has stuck with the same formula for decades of wall garden and control of both hardware and software. That business model failed spectacularly, then treaded water, and then succeeded spectacularly. I think none of which was from an insightful or brilliant business analysis, it was just how the stubbornness played out.
So as for where it will go from here, I think who knows. Phone hardware is now powerful enough that you don't need the same hardware and software vendor where it needs to be so tightly controlled. But Apple has built itself a nice market which is kind of self sustaining. Will people care about prices again?