I don't own a cell phone but my son's £1000 iPhone goes everywhere with him - until it gets broken, lost or stolen, which has happened on average twice a year for the past 10 years.For sure smart phones have become the camera of choice for hundreds of millions. They're ubiquitous and everyone has one with them at all times and they are all that a lot of people need for a camera.
DSLRs are dying out because of a technology advance in sensors which obviate the need for a mirror that flips up and down. Mirrorless cameras are taking over the prosumer market because of technology, size and weight advantages. There are a lot of other things going on in the camera market such as prosumer cameras now also do a great job with 4K video.
Technology marches on.
Side note: Kodak is reintroducing Ektachrome film so nostalgia sells as well.
It doesn't take bad photos either and is invaluable when it's on hand to record an accident scene or the sudden emergence of a wild animal from the bushes. But I would guess that no designated amateur photographer would have one as his weapon of choice. And it's no good for photographing my roof. And it's a pain in the neck when you're trying to enjoy a quiet round of golf (but not as bad as the Motorola brick which used to hang off my golf buggy 20-odd years ago).