I'm confused about what represents a single point of failure? Taking advantage of the cybil attack?
It's a mistake to think that we can increase this above 50% without ending up some other imbalance. 50% is the hardest to attack in either direction (stop something bad/undesired or prevent something good/desired)
Despite all this, I think our community is slowly starting to recover its historical validators and has managed to get rid of the one that was set up by Justin Sun. However, the latter has not said his last word! Case to follow.
We definitely need to pay attention to this. It's not worth giving up without a fight. I hope he comes to realize that by cooperating with the majority we can have a win-win. I don't see a case where he wins and we lose, and the chain survives and thrives.