It doesn't mean there isn't any improvement. Phone cameras are getting so incredible now that you really don't need to carry a P&S and with things like HDR+, OIS, 4k video you'll get better results.
People have been saying that smartphones replaced cameras for years, but now they are not just a replacement but actually better.
There has still been innovation with dual cameras, finger print sensors, laser focus, better LED flash, USB type C and monthly Android security patches will probably encourage people to upgrade after they reach EoL for a device.