Futures markets are being hailed as a net positive for bitcoin, introducing institutional liquidity to the market and providing a hedging mechanism for businesses, miners, and speculators. However, the presence of this market can also, theoretically, introduce new attack vectors.
The first of these attack vectors is known as a 'Goldfinger' attack. 
Many discuss the potential for nation-states to eventually become involved in mining. But, as governments are able to absorb or tolerate large losses to accomplish a goal, they, as miners, may introduce new factors to consider as well.
In the current monetary regime, the US is able to control money flows and blacklist "bad actors." We see this with Iran/North Korea/others. Theoretically, if they became involved in mining, they could co-opt the system to their benefit. An example is a Feather Forking attack:
In the immediate term, a Goldfinger-type attack would be more probable once futures markets mature. Feather forking, in my view, would be much further down the line, assuming say, a nation state got heavily involved in mining. This is still a ways off, but is possible.
The reason for this thread is not to cause alarm, but to be cognizant of near and long term threats to the network. Additionally, as I've stated before, there are credible, technical critiques of the network beyond just yelling "bubble" without any substantive discourse.
I've presented two basic ones here. I am sure someone with more technical expertise (or game theory expertise) than me can weigh in on additional factors or probabilities. But at least that's a credible discussion instead of the tiresome platitudes offered by most outsiders.
In closing, it is important in times of market bullishness to remain vigilant and grounded. We have come such a long, long way, and there's still a long way to go. It's important to have a long term view not just of the upsides, but how risks will evolve as well.
In any investment, you should spend the majority of your time searching for things that challenge it, instead of things that support it. You should be your most qualified, fierce, informed enemy.
For those asking for the source of the extracts, here: bitcoin.ninja
For those asking for the source of the extracts, here: bitcoin.ninja
