I dont think UV mapping will ever go away. Its really the most efficient way to paint things. Some shapes are really complicated to paint on a 3d Surface.
Ain't nobody got time for that. Only hero assets can really take advantage of 3d painting, but for most hard surface or enviroment assets, probably not worth the time. A asset may get a quick pass in a 3d painting app, but the bulk of the work is going to be with photoshop, substance designer, or dDo.