This should be good news. Less people have to slave away making iPhones because everyone has got one and less people have to slave away paying for getting themselves a phone that does everything they wish for in a phone. Yet with the wonders of capitalist growth this is met by the people that write for the media as a concern. Every curve has to be exponential.
Take the Pixel XL from Oct 2016: 5.5 inch screen, 2560x1440, 4GB ram, quad core CPU, 128GB of storage. The pixel 3 XL isn't much different (same ram, same storage, 10nm CPU instead of 14nm).
If apple keeps offering the $29 battery replacement I'd expect the average iphone owner will keep them for significantly longer. They already claim about $9B of losses because people are replacing batteries instead of buying $1k phone replacements.