"if Bitcoin drops below $1,000, mining now becomes unprofitable, rendering a very large part of the entire Bitcoin mining infrastructure instantly obsolete."

If this were true, the entire shale patch would be obsolete and nonexistent, which is manifestly false. A bitcoin price drop below $1000 would mean one of two things:

1. The cost to produce drops below the commodity price.
2. The commodity is no longer mined.

Neither would be an immediate outcome, as the author suggests. Most likely scenario would be a shakedown of the miners, where only the most efficient would survive, as suggested by Stan.