I wonder about the effects in Eastern Europe and North America and the Muslim World.
For example, the Irish War of Independence heralded the Hungarian War of Independence of 1867, which turned into a regional war (Russia/Serbia/Montenegro/Hungary VS Austria/Germany/Romania), and ended with Poland in German hands, and Austria keeping the entire empire except Hungary itself.
Then, in 1898, the Crete Crisis caused the Balkan War.
Initially Greece vs Ottomans, but Serbia, Montenegro, Hungary and a reluctant Romania (pressed by all neighbors) joined the Greeks, and then, Italy took advantage of the situation to invade Tunisia, Libya and Egypt.
Russia unofficially supported the Balkan Coalition but was busy shoring up its Abyssinian protectorate against the British. In fact, Russia only participated at the very end and on a peripheric theater, when Italians were in Cairo, and Madhists had taken Sudan (a Russo-Abyssinian force took South Soudan).
Britain was in no position to intervene, as the British were busy quelling the Boxer Rebellion, which ultimately failed to topple the Anglo-Japanese condominium on China. They were lucky that Boxers didn't believe in firearms, as China is really big...
So, the result was that the Ottomans lost all European and African territories, either to its enemies or the new Bulgarian state. And in return for Hungarians helping for free in 1898, the entire Balkan Coalition would help Hungary against Austria in WWI (it didn't stop the Austrian side from winning but still).
China would prove a poisoned chalice, as the USA openly supported Chinese independence (and was against Anglo-Japanese control) and provided weapons to Chinese nationalists.
Which would lead to Japan launching the Pearl Harbor attack during WWII, and in return, the USA declared war on the Tokyo-Berlin-Vienna-London alliance, leading to its defeat.
And finally, North America... The CSA, the greatest mistake of London. It earned Britain the enmity of the USA (well, that, the Chinese problem and re-annexing Ireland in the 1920s), and led ultimately to the defeat and the catastrophic Treaty of Washington. And in the meantime, the CSA had to be propped up economically and militarily, and were a major diplomatical embarassment, as the Southies knew that Britain needed them to counter their common US enemy, and so they never ended slavery (Britain could yell at them but it was empty as they knew London couldn't drop them).
So, if 1848 had been different, would the Roman Empire have been restored from Slovenia to Wales (in personal union) to Egypt ? Would Scotland have ultimately joined the Scandinavian Union as the fifth member ? Would the Ottomans have reformed enough to keep Mesopotamia, Arabia and Levant to this day ? Would France have become the only communist monarchy to exist ever (as a compromise between communists and monarchists among the Résistance during WWII) ? Would the Windsor family now live in Japan, within the Imperial Court ?