Not a nation per se, but the French aristocrat Alexis de Tocqueville in Democracy in America predicted back in the 1830s that Russia and the United States would be the great powers of tomorrow, due to their growth and unmet potential.

The relevant quotation is as follows:

"There are now two great nations in the world which, starting from different points, seem to be advancing toward the same goal: the Russians and the Anglo-Americans. Both have grown in obscurity, and while the world’s attention was occupied elsewhere, they have suddenly taken their place among the leading nations, making the world take note of their birth and of their greatness almost at the same instant. All other peoples seem to have nearly reached their natural limits and to need nothing but to preserve them; but these two are growing…. The American fights against natural obstacles; the Russian is at grips with men. The former combats the wilderness and barbarism; the latter, civilization with all its arms. America’s conquests are made with the plowshare, Russia’s with the sword. To attain their aims, the former relies on personal interest and gives free scope to the unguided strength and common sense of individuals. The latter in a sense concentrates the whole power of society in one man. One has freedom as the principal means of action; the other has servitude. Their point of departure is different and their paths diverse; nevertheless, each seems called by some secret desire of Providence one day to hold in its hands the destinies of half the world."

Source: ALEXIS DE TOCQUEVILLE, Democracy in America, ed. J. P. Mayer, trans. George Lawrence, vol. 1, part 2, Conclusion, final paragraphs, pp. 412–13 (1969). Originally published in 1835–1840.