What action can governments take?. The cat is already out of the bag. The only reason we are seeing so many comments which are opposed to the $100,000 EOY scenario is because humans tend to struggle with the concept of exponential growth because we are hard coded to think in linear terms.
One year is a VERY long time in Crypto and 2018 is likely to be the longest year weve had yet. Bitcoin became mainstream in 2017. 2018 will be the year that mass adoption takes place and there is no reason to believe that a $500,000 btc is not possible.