The modern world is a peaceful place, bereft even of entities capable of waging the sort of wars which cut short the lives of so many past generations of people and pokemon. However, if the Violet Book represents an accurate account of the future, we must acknowledge that peace is not humanity's end state, for there is no interpretation of Iron Treads other than as a war elephant built by some sort of later generation.
Donphan and Copperajah were used as war pokemon for most of warfare's history, and only in humanity's final conflicts did anyone invent artillery with sufficient power to drive them from any battlefields. A sort of mechanical vehicle called a "tank", named for its inventors' ace Miltank, attempted to fulfill their role late in the conflict; the term survives in the language as a metaphor for a stout defensive pokemon, but the vehicle's lack of attack power made it more valuable for delivering pokemon than for fighting on its own.
Combining these "tanks" with Donphan remains a logical step for the next war, but fortunately, armaments have died out as a branch of technology in our time; it is noteworthy that some of that war's most innovative generals sketched something remarkably similar to Iron Treads. And it should not be forgotten that robotics has advanced immensely in this peaceful age. It is true that the notion of fully mechanizing a living pokemon is today considered impractically expensive and dangerous, but governments of the past spent astounding sums on weaponry, and necessity is the mother of invention.
Of course, it could all just be an elaborate hoax, or a future which never arrives; I, for one, do not wish to ever see Iron Treads or the bleak world implied by the Violet Book ever come to pass.