Well you need to look at the immediate effect - the war was basically about hegemony and control of Korea, so a Chinese victory would reinforce the vassalship of Korea to the imperial throne. You would thus not the delusion of grandeur in Seoul that led to the short-lived if highly aspirational Empire of Korea.
Japan has been taken down a peg and will take time to rebound to even where they were - they will rebound, but its a shock and they probably have missed their chance.
China may or may not now be on a collision course with Russia since the Russo-Japanese war effectively came from a collision of interests, prime among which was the question of rights in Korea, including along the Yalu.
Forgot all what I was going to say before my meeting started now; ah well
Beset Rearguards
Grey Wolf
Grey Wolf
Sounds fairly likely and the last one could be a big one. If China gets into a rumble with Russia I can't see Russia losing but I could see other nations, most noticeably Britain seeking to intervene to protect it's own economic interests and preventing the Russians gaining too much territory.
You might just see an Anglo-Chinese alliance, although this is probably less likely as China is far less modernised culturally and unlikely [the old regime anyway] would look for an alliance.
Could still see an alliance with Japan as the latter will be even more eager for an ally and Britain will be looking to rein in Russian interests. However as you say likely to be less an alliance of equals. [The possibility however of China opposing such an alliance between it's main trading partner/investor and a recent and bitter rival].
If a Sino-Russian war occurred about 1904 then that could scupper the spreading of the entente to resolving differences between Britain and Russia, who are likely to be at loggerheads. That would make the alliance system in Europe a lot more complex as Britain could stay a wild-card.
Just thought as to what a Chinese victory would do to the Boxer rebellion. Suspect it wouldn't be avoided and might be more likely and earlier because Chinese emotions and confidence are heightened. More dangerously it might give the dowager the confidence to support the rebels against the Europeans openly, rather than staying on the fence. That is likely to have hasty effects in China, especially if it means the foreign quarter falls and there is a massacre.
Steve