The phone camera user will inevitably become dissatisfied with their pictures, and will buy a DSLR.
which is a very cozy idea. There's a couple of planted axioms, unfortunately. The first is that the cell phone user will become dissatisfied. Nope. The second one is that the dissatisfaction will take the form of some very specific limitations. The conceit is that the disgruntled cell phone shooter will want more IQ (nerds invariably refer to "image quality", which simply means "the vague basket of shit my DSLR does better than an iPhone", as IQ).
I'm just gonna throw this out there: the disgruntled, dissatisfied cell phone photographer is actually pretty unlikely to say "man, I want to take pictures with more pixels in them!" They're a lot more likely to say "I want to make pictures that make people feel", "I want pictures that make people see this truth that I see", "I want to make pictures that look like that one guy on tumblr."
These are not problems solved by buying a DSLR.
The ones that do want to take pictures that have more pixels in them are sorting themselves into the community of online DSLR owners. They enter the bubble, close the door behind themselves, and there they are.
The ones that want to take pictures that make you feel something, they're doing something else. They're getting apps for their phone to bend their pictures. They're buying Polaroid cameras, old p&s film cameras, Lomos and Kievs. They might even buy a DSLR, but they think the debates about sensor size versus depth of field are deadly dull.
These are the people with the kickstarters that are publishing books. These are the people with their photos hanging in the hipster coffee shops. They don't care about your sneering "these are terrible, they need fill flash" judgements, because you are wrong. These pictures don't need fill flash.
There's a 1000 directions to go from a cell phone camera you bought yesterday. Only one of them is a DSLR, a bunch of expensive lenses, some cheap strobes, and a flickr full of crummy imitation commercial photographs.