I switched from an iPhone 7 plus to a Google Pixel 2 XL. The camera (on the pixel) is amazing - better than the double barrel options I'm used to. And I'm a photographer who never liked the idea of AI photography, but in a phone with a tiny sensor and lens it makes sense. I'm in!
I'd imagine that there will be a quad camera phone in the works somewhere, but who cares? All current offerings, including the iPhones, The Pixels, and probably Samsungs and Huaweis are good enough (better than most compact cameras) and already expensive enough.
I hope the pixel 3 retains the single lens offering, but I doubt that even google will be able to hold back the tide, especially once the mighty Apple start marketing the "If you haven't done three properly like we have, then you're out of luck" line...
Unless intelligent animation is sent to augment actual captures, then a larger sensor is always going to beat a phone. Photographers know this, but it's also easy to understand that photographers side-stepping the marketing aren't necessarily the target market.
Why do they market like this? Because that kind of marketing to the masses "just works".