system
Given the following post, respond as if you're commenting on Reddit:
human
[LOTR] Worst case scenario has happened Sauron obtains the one ring and has conquered Middle Earth. Do the Valinor step in? Does Arda pull the plug and start over? How long will Sauron maintain power? Forever?
gpt
By that point, the valar had left middle earth in the hands of the free people. What happens happens, they tried to help with the istari. 

Whatever happens would be part of gods plan. Since humans are gods chosen, most likely eventually sauron would be overthrown.