He has some points, but there 1 problem with his reasoning; he goes on and on about miners leaving (hashrate dropping).

He does not understand network difficulty. It will go down when miners leave up to the point where it's profitable again. This has happend in 2011 too when the large crash came (and GPU miners were running below cost at $5 levels). Wish I was into the game back then...

It's a triangle of hashrate, power costs and bitcoin price.