people are hanging on to phones for longer
That's no surprise. Like with PCs and laptops, the market is now mature and the new devices are not significantly better than the older devices, year on years.
Average lifiecycle of PCs and laptops went from 3 to 5 years nearly 10 years ago. Now the same is happening with phones. The big boys will have to learn to cope with the "new normal" 9see what I did there?) or the new names in the market building cheaper kit will eat their lunch.