The main reason to buy a new phone these days surely is "the old one broke". Being with us all the time. The planned obsolence - unreplaceable battery, glued screen, glassback etc mean phones break all the time.

PCs stand still, even laptops tend be mostly stationary. No wonder my work laptop is now 6 years old and I feel no urge to request upgrade.

Which is pretty much where we are now. At this point smartphone sales are mostly based on making performance more affordable, and lots of marketing.

People drop their smartphones more often than their desktops.

But I expect cheaper devices to take more share, since the "high-end" won't give you much benefits over them. My 120 EUR Xiaomi already offers amazing cost performance compared to most other Androids.