On the other hand AlphaGo proves that computers can scale, even if they are inefficient, whereas the only way to grow that 20 Watts brain would be to use multiple brains and that's not going to be any good in Go matches.
On the contrary, I think there is a real question over whether AlphaGo would be able to beat a group of 3-5 tier-1 Go players (e.g. ~top 10 rankings players) who were allowed to write things down on paper, discuss, use whiteboards, use separate game boards to play variations, etc, even with same time controls.