Let's see:
Bonepartist France: Napoleon was killed while on campaign in Russia, leading to a Regency with his son as nominal monarch and Josephine and Talleyrand as dual regents. Italy remains a puppet of France
Secessionist North and West: A Supreme Court ruling that strikes down any antislavery law as unconstitutional causes a national firestorm, as whether or not to enforce it becomes a defining issue in the 1856 presidential election. The slaveocrat wins, a second Hartford Conference takes place as the New England states secede, with the rest of the north following suit, forming the Federation of American States. The new nation annexes the Dominican Republic, Hawaii, and purchases BC, Alaska, and the Phillipines.
Ottoman Empire: A series of reformist sultans rule. Traditionalists attempt a coup that fails and breaks their power base. in the 1830s they fight off a French invasion of Algiers and the sultan uses this as an excuse to tighten control over North Africa. in the 1870s the modernizing empire establishes a parliament which gains more and more power over the 20th century. With vast oil supplies and the Suez Canal the Ottoman Empire is considered a superpower.
United Provinces of the Sunda Islands The Dutch East India Company fights off a British invasion and intermarries with the natives. Dutch becomes a prestige language, though the majority of the population continued to speak Malayan until the early 20th century. In the 1850s many Cape Dutch who chafed under British rule traveled to the Sunda Islands, as did many Dutch who had fought for Dutch independence from France during the Year of Revolution.
Indian Federation In the 1920s India is given Dominion status. over the course of the next 80 years, the country rapidly develops, vying for influence with the Turks and Chinese in Central Asia, and with the Chinese and Sundans in Southeast Asia. Urdu is the prestige language, taught in most schools alongside English.
Brazillian Empire: When Bonepartist France installed a puppet king in Portugal, the native dynasty fled to Salvador in Brazil. There they stayed, eventually abolishing slavery in 1882. Brazil was another major power, along with Sunda and the secessionist Americans, that benefited from the emigration of those on the losing side of the Year of Revolution.
Federal Republic of China: In 1898, in response to growing western influence, a revolution overthrows the aging Qing Dynasty. A strong government kept the country together and successfully played the Russians, French, and British against each other. They found a surprising ally in the form of the Sundans, who gave military and naval aid to the new country in return for trade concessions. Over the course of the Twentieth Century, as colonialism declined and the nations of Southeast Asia became independent, this alliance broke down as they competed for influence.
United Kingdom of Britain, Ireland, Canada, Australia, and the Cape: An amalgamation of British dominions, this county is considered a waning power. After the first Emperor's war, Home Rule was granted to Ireland, and Canada, Australia, and the Cape were given Dominion status. After the Second Emperor's War, in 1939, they were elevated to kingdom status.
For the fate of OTL powers:
United States: the Free Stats and territories seceded. Afterward, the planter aristocrcy fought harder and harder to hold on to power. Allying with the French in the First Emperor's War, they were invaded by FAS. A communist revolution overthrows the planters, and make peace with the FAS, ceding Maryland, Delaware, Polypotamia (southern Illinois), Kansas, and Missouri.
Russia: Russia suffered greatly after the Third Emperors War. With an invasion of Russian-occupied Europe defeated and hundreds of thousands of soldiers killed, along with definite knowledge that the mass slaughter of Germans, Poles, Hungarians, Jews, Muslims, and Greeks were taking place, it was decided to destroy Russia. As a result, the Carthage Offensive was launched, as Kiev, Petrograd, Moscow, Tsartsyn, Novosibirsk, Omsk, Kazan, Kiev, Minsk, Pskov, Ryazan, Archangelsk, Astrakhan, Irkutsk, Sevastopol, Odessa, and Riga were destroyed by a nuclear offensive. Large parts of Russia's breadbasket were seeded with anthrax. Nearly half of Russia's population died in the ensuing famine, the Central Asian kingdoms go their own way, and Russia proper is the domain of warlords and petty tyrants.
Italy: Never unified. Subjected to the same mass enslavement and slaugher the rest of Europe was during the Third Emperor's War.
Germany: Unification comes in 1959, at the end of the Third Emperor's war, after nearly 40% of the population was killed in the Ochitska (Russian for cleansing)
Japan: Puppetized by China after the First Emperor's War.