I think the trouble is that the devices are getting too good and there is really only incremental improvement every year so the upgrade cycle is getting longer. I typically get the latest phone every year (but it starts to feel unnecessary) - iPad's and Mac's, however, last a lot longer (several years) for me these days. I wonder where the real innovation is going to come from? AI, AR?
If you are looking for something as big as the iPhone, I think you might be disappointed. But, it is a pretty poorly kept secret that they are working on self-driving cars and some kind of "TV".
And Apple has been pretty clear about focusing on growth in services now that they have this massive base of deployed devices.