If powerlines could have negligible resistance, then it will be viable to transmit power as DC. (At the moment, AC is used to minimize power loss during transmission.) This could mean that devices could plug into a (say) 12V DC outlet right in the wall, eliminating all the heat loss from each individual transformer, and getting rid of the bulk. Imagine, your computer wouldn't need some massive AC-DC power supply! (Obviously it'd still need a small, simple one to transform down to 5V, etc.)