A pretty good article that explains about the slowdown of the mobile phone market (04-01-19)

https://www.livemint.com/Companies/nthPChv79NaAuuvnbCFuUO/Slowing-iPhone-sales-a-wakeup-call-for-the-smartphone-indu.html?facet=amp&utm_source=googleamp&utm_medium=referral&utm_campaign=googleamp

I also think that nowadays the phones have been offering lesser and lesser breakthroughs while increasing the price tag tremendously.