Black Swans are....painful. Deep jump skews. Depending on how you are positioned, either its a fabulous day or a stunned mullet day. Taleb obviously had a lot to say. I would point you to the Sante Fe institute for research in complexity theory for a really colourful way of thinking about it. They brought together heaps if discliplines to figure out things like why crowds do crazy stuff, how DNA/RNA might have first formed. All of these are Black Swans and it is useful to grab everything you can. One of my favourites is the Sand Castle analogy by the now-deceased Per Bak. You could code it in a few hours and watch it unfurl. And there you have an analogy for the kind of scenario you are metioning and pretty much anything you can imagine.
I also am a believer in Minski whose thesis is another way of saying Black Swan.
Any deeply integrated system which involves people or any positive feedback is susceptible to Black Swans. The bigger that system, the bigger the potential event is. Financial markets and underlying economies, government and populace are all linked and hence this fits squarely into those requirements.
Black Swans dominate your return profile. Everything else hardly matters in the end. That's why stock returns are highly leptokurotic and skewed for short time periods. It's why options trade with skew for near term maturity, including in banks given the credit risk they bear is largely a blow-up risk.
They will happen and, as you say, the longer you go, the greater the likelihood you will encounter one. So what do you do?
Diversify. Hold lots of stuff and, if they are somewhat uncorrelated, then you can survive the bumps. But that's not enough, because correlations jump and effective diversity declines in sharp moves. So here we get closer to something interesting. How can you ensure that diversity will exist in a correction? After all, that's when diversity matters most?
You suggest that value would be loaded into Mining Services and this might be an aggregation of risk. If this is right, you will observe decreasing effective diversification within the Mining Services group of companies. That is, the correlations between the stocks will increase. That's a bloody big warning sign. The same could be said of any sub-group of stocks that you could be concerned about. You now need to adjust your portfolio to increase diversity if this is happening. I wouldn't just use numbers. I would be like you and think about it. The right answer is judgment based. I would not hesitate to put on positions that were not supported by statistical outcomes if I thought it was right. Statistical tests do have error in them and knowing when it is a false negative and likelihood of that being the case is an important judgment. It could also be that you know that the underlying systemic structure is poised in a tense state but simply has not encountered the kind of circumstance that would lead it to be visible in market prices. Use everything you have at your disposal! And even then we'll massively fail to catch a lot of things that go bump in the night.
There is also auto-correlation in volatility. This is harvested by people who use GARCH type time series models or others like it like EWMA etc. You can also spot it in options implied vol. In reality, you need both because neither are particularly dominant over the other and a combo proves the best way forward in general.
After all that, you move to tail risk hedging. Put a floor under you. If you can't hack it, protect it. Lay the risk you cannot bear off to the guy who can...and can back it.
Also...having a long time horizon is one of the best things you can bring to the table. This is longitudinal diversity. Those deep skews and other bad behaviours of stock and other security prices, they largely disappear when horizons lengthen. If you can do that, things look pretty tranquil. Rolling 20 year returns don't look very bumpy do they? Rolling monthly ones look shocking.
How do you stop manual overrides from being abused? One way is to be explicit about why you have the override, the kind of evidence you expect to see if this is true and a time line for removing it in the absence of contrary evidence. I don't have a magic solution. This is the area where people distinguish themselves from each other. It's a judgment and often, those judgments are wrong.
I think the biggest thing is that you have to stay alive to play. There is no certainty about the magnitude of Black Swans, so you need to know your butt is covered and this comes at a cost. Or you can self-insure and hope the big one doesn't collect you before you depart this planet.