[nemochev]

"So currently mining Bitcoins requires power levels somewhere between the one produced by the Hoover Dam, and the world’s larges coal fired power station."

Emphasis on "currently"

Disruptive technologies are almost always costly in some way or another until more widely adopted.

[bct]

Show your work. Why do you expect the power consumption of the Bitcoin network to go down?

When specific costs of a technology decrease it's for reasons specific to that technology. Yes, cell phones have gotten smaller & less expensive (as one example), but that doesn't tell us anything about the power consumption of the Bitcoin network.