The mobile phone in its current iteration is plateauing. Their usefulness is limited by the size of the screen and how data can be input. Tablets and Phablets, by having larger screens, are more useful but still fall short of a laptop for serious work. By work, I mean creating content and not simply consuming it. I don't see the Android OS as having enough depth to use on a laptop with a comparable functionality to Win or MacOS. If Google wants to start walling off functionality for their exclusive marketing, they will open a door for a competitor. Right now, it would be too hard to get any traction as a third mobile OS provider. Even M$ isn't doing very well at it and a big part of that was coming late to the party with a product incorporating a UI that looks like it was designed by Fisher-Price.
Phones are a commodity now. I have a an off-brand phone that does everything I want it to do. There is nothing about an iPhone or the Pixel that makes me want to rush out and pay over 10x the amount of money to own one. This week I plan to buy another copy of the phone I have as a back up for around £60. I'm not a Royal or a bank robber so having spare iPhones or top of the line Samsungs just sitting around isn't in my budget.