Actually based on actual history, nations and "major powers" often come into being for a variety or combination of reasons.
1) Military power
2) Economic power or monopoly control
3) Trade or trade control
4) Population (almost never as a primary cause, but as a secondary influence)
5) Technology- monopoly or superiority
6) Radically different military theory
7) LEADERSHIP
The British Empire, for example, got its foothold due to superior technology and military theory landing them with the best Navy in the world. That in turn led to them to naval military superiority, which was exploited into controlling trade (after smashing the Dutch) and there by becoming the dominant economic power.
Despite that, once the Empire hit its peak post-Napoleon, it only lasted another 100 years before declining rapidly.
There are other analogs. For example, saying Scandinavia could not be a major power isn't actually accurate. Individually, Denmark, Norway, and Sweden were all major world powers at points in history. The purely mercantile Hanseatic League dominated the Baltic for centuries, and wound up controlling land, armies and warships through its evolution.
The other contributing factor is leaders and leadership. If you had talked to anyone in the "modern world" of the Pre-Alexander hellenic world, no one would have belived you if you had told them that a minor semi-barbarian kingdom like Macedon would become a major power in just under 25 years under Phillip II of Macedon. His son used that major power status to springboard into the largest world power of its day.
No one in world of 1900 would have belived that an Asian state could defeat a modern European power. Yet Japan in 1905 did exactly that and handed the Russian Empire a defeat that destabilized them for decades. Despite the fact that 40 years previously, Japan had been a backward feudal state. In less than generation they had gone from a feudal state to a world power.
On a darker turn, Post-WW1 Germany was a failed state. Yet in the space of a decade, on charismatic madman was able to turn that state into a world power that threaten the world.
When you throw in the combination of completely new tech (Trans-Newtonian) and a complete change in energy and transportation that results (huge economic shift) along with stable to inspirational leadership, you could have almost ANY country show up as a world power in a Trans-Newtonian Aurora universe.
For example, from a previous game of mine that extrapolated a world devastated by plague (based on plague era Europe) one of my powers was Scandinavia:
Skandinaviska Unionen: Formed originally by Sweden, Norway, and Finland, the SU expanded and began incorporating portions of the Baltic States, Denmark, and portions of northern Germany and Poland, the Kola Peninsula, and Karelia, Icleand, and most recently, Greenland. The SU is nominally socialist, with extensive social programs, but with a very vigorous capitalistic bent. The SU had functioning military industrial facilities after the Plague Years and made a considerable amount of money selling munitions to groups outside the Union. The SU military is one of the best equipped and best funded, and they The SU has glimmers of pre-war Scandinavia, but by and large they are a very practical and pragmatic group. The SU has been aggressive in perusing the new technologies that have been discovered and they are not backing down from the threats posed to them by their regional rivals. Unlike several of the other regional powers, they SU has generally been invited into areas by popular vote and concessions.
The African Union COULD be the template for a Trans-Newtonian world power. Assuming Africa wound up with a sizable amount of TN materials, in conjunction with a sufficiently visionary and strong leader or leaders, it could transform into a major power in a fairly short period of time.
There are certainly arguements, and good ones, that current states COULD be world powers in a TN era. They could also be displaced by a currently third world state that winds up with TN materials and the leadership to exploit them successfully.