8 gigawatts is a lot.
Blockchains don't scale. Period. If you know of a way to make them scale, publish it and you'll find instant fame and fortune.
The power consumption will continue to increase, and that is purely the fault of POW.
If that's your position then changing the POW won't help.
(I know no one cares, but there could be a pragmatic scaling path where you increase on-chain throughput while you do sharding/layer 2 research.)
They don't need to scale linearly with off-chain transmissions acting as a secondary transmission network.
8 gigawatts is a lot.