I mean, one route--the most depressing of all--would be the absolute disintegration of the human proclivity to value art. I doubt this, though; even with the use of technology, innovations will always come and therefore be able to distance themselves from others and create sign value. Even if this sign value is produced by AI, it still exists (as much as sign value of art produced by another human). I suppose here is a situation where death of the author comes in handy!

And regarding cost/skill difference, I'd argue that in photography there's a different type of skill. A photographer has to find some scene such that the image has good composition and the likely uncountable other elements that go into a photograph (or at least an aesthetically pleasing one by common standards). Not to mention that the more money one invests in painting, the easier it is to paint. Paintbrushes, for instance, are a perfect example of this. Also, having all the colours you'd even need removes the skill element of colour mixing, too, so in a number of regards the ability to produce "good" paintings is contingent upon expensive tools, too. Both media have similar but incomparable elements of skill and, to some extent, cost (cost is comparable in the sense that it's a linear value that can be compared, but how that converts into art is dependent upon other things, also).