About five or so years ago, I read an article about how adding video capabilities and using larger storage cards to DSLR cameras was becoming a real boon to amateur and small budget film makers. They became cheaper to own than it would cost to rent more traditional movie making equipment and filmmakers still got a lot of the benefits such as higher resolution, swappable lens for various depths of field, and videos in a digital format that allowed for easier playback and editing. There were of course drawbacks, but reintroduce of equipment, they were real bargains and often a very smart choice.
As the cameras and the software on phones get more and more sophisticated, it makes a lot of sense that they're becoming a tool for filmmakers as well. I think it makes some sense that there tiers of equipment use will develop, from "real" film making equipment being on the high end, to DSLR being on the mid end, and phones being on the low end.
Naturally, as with anything in art and creativity, there will always be the discussion as to how the tools and equipment used will lead to better or worse final products and to how much that actually matters and why.