If Russia loses it will still be very bad for Russian influence for decades. It will be seen as Putin's self strengthening movement failed just like Li Hongzhang's. Ukraine, while poor, will have propaganda and aid propping it up.
Already Mongolia is switching to Latin letters instead of Cyrillic (Russia) or classical Mongolian (China). Kazakhstan is switching to Latin letters instead of Cyrillic (Russia) or Persian (China). This is just like Vietnamese switching to Latin letters and Koreans banning hanja. Russians failing to win here is like Qing losing Vietnam to France and Korea to Japan.
This is bad because weakness invites aggression. Humanity might not survive the Russian version of Second Sino Japanese War.