A solution for oracles will most likely be that an default (centralized) oracle can set an outcome first but there will be an objection period. If someone has an objection (and makes a deposit) another more reliable (and more costly) service should be triggered. If this option is given and the “last resort” oracle is widely believed to be 100% uncheatable than it might get never user.
So to have such an oracle would be extremely valuable.
So lets think about the “ultimate oracle” - the most secure one that can be made. For the security it is important to see what people who determine the outcome have at steak. In the case of Augur it will be the REP tokens, in the case of a human Twitter oracle it will be its personal reputation (maybe there is an real world value bigger than what is measurable on the blockchain but if we would purely look at the blockchain it would be the future income from this reputation - or other benefits that comes along with good reputation)
The ultimate oracle would want to make the amount as big as possible - so a radical idea would be: lets put potentially all Ether at stake. It could work super simple: if the ultimate oracle is triggered (only with a decent fee - payed by a) the first person that did the initial wrong settlement and b) a person who challenges the outcome) ALL ETHER HOLDER can “vote” by putting Ether on the outcome they think is the correct winner/answer.
So lets say we have a future dispute whether or not Trump was elected in 2016 - the first (wrong?) settlement said “yes” and is backed by 100ETH and than a objection fee is payed of 1000EHT on the right answer “no”.
Now anyone could send money to “yes” or “no”. The process stops if after lets say 48h “no” is still in the lead (more Ether is send to “no” in total. As soon as “yes” gets in the lead the process will continue for at least another 48h. If the frontrunner is not changed for 48h the result is set.
Why should this work? So in principal this is an symmetric game. What breaks the symmetric is that a) the truth is the natural point to coordinate on and more importantly b) the people betting on the truth can make a credible thread of forking Ethereum if they loose.
Because if it really gets big (and it could escalate quickly) the value of Ether in general is at stake. Who would want a system where just 30% (e.g.) of the total value of the currency was redistributed from honest voters to an evil alliance. In this extrem unlikely case the 30% would most likely just fork Ethereum from a state before this “disaster”. I expect that to never happen because it will be way easier to coordinate on the truth and just to collect the “100ETH” the person gave as an security deposit initially.