Apparently there was a writing of “The Prophecy” in the 2019 book Master & Apprentice, which is considered canon:

"Only through sacrifice of many Jedi will the Order cleanse the sin done to the nameless.

The danger of the past is not past, but sleeps in an egg. When the egg cracks, it will threaten the galaxy entire.

When the Force itself sickens, past and future must split and combine.

A Chosen One shall come, born of no father, and through him will ultimate balance in the Force be restored."

Which I know they were writing it after the fact to make it fit the Prequels, but it kind of spells it out pretty clearly that a bunch of Jedi were going to die before “balance was restored”, but maybe for most of the Jedi this prophecy was so old that it was like a myth or a fairly tale that many just assumed would never come to pass. It almost seemed to be that the extinction of the Jedi AND the Sith was the “ultimate balance”, but I doubt they’ll give up the ghost of the Jedi just like that. Not sure where Disney will go with it, as they’re meandering pretty slowly through the timeline, though the next SW movie with Rey Palpatine Skywalker is supposed to take place 15 years after Ep IX, so I guess they’re finally moving to push things forward.

I don’t have anything to add, but I’m interested in the conversation, so here I am.

Is your body in balance when there’s an equal number of cancerous cells? Is your garden in balance with an equal amount of weeds and crops?

This question pops up seemingly regularly among fandom hubs, and it never considers that balance in The Force isn’t an algebra equation. Even with the Rule of Two limiting their numbers, the Sith steadily fomented corruption, fear and misery in the Galaxy building into all out war and fascist oppression.

The Jedi’s failure to respond had nothing to do with their numbers, but with their rigid adherence to dogma robbing them of the tools necessary to address the threat. Dozens of Jedi had spoken up about the rising corruption and might have been effective in fighting it were the Council not obsessed with protocol, optics and precedent–just letting Anakin access the restricted texts would have made all the difference.

Sidious was uncommonly powerful, but he didn’t collapse the galaxy on his own–a string of Masters before him used a philosophy centered on aggression, deception and abuse. They take power by making things worse for others meaning their presence is a net negative for the Galaxy at large.

The Sith are a cancer, and you don’t leave cancer in a body if you want it to stay healthy.