95% of miners are suddenly offline.
Be it a new law or an EMP strike. What would happen to bitcoin?

Most EMP strikes are trivial to defend against with a properly grounded Faraday cage. Many datacenters are protected against EMP's as well.
Can your power grid handle a Solar flare of X-Class higher than 40? Do you know, that it will happen one day, and will be aimed directly at us? Do you also know it has happened in the late 19th century, but thankfully back then we were not as advanced as we are now.