She’s not wise and she never really beat anyone. The other air benders defeated Zaheer, weird spirit bending happened with Vaatu and Amon was killed by his brother. Everyone seems to do pretty well without her.
It would be so cool if they ended the series with the next avatar being reincarnated as one of Toph’s great grandchildren or something. Yes I am aware that this is the last series. Any avatar would be better than Korra. Even Kyoshi. Kyoshi scares me.