Silver would not have a great impact on the conductivity unless you are dealing with very low current circuits, in which case gold will be used (as in computers). Silver is a harder metal than gold or regular solder and thus it is used to braise metal pipes. I do not see it having a future in electrical, but as the other guy said, maybe ask a plumber. Copper on the other hand is quite a good conductor, however it is quickly getting replaced with the likes of aluminium as it is lighter, cheaper but is slightly less conductive. Therefore i cannot see copper increasing too much in the near future as aluminium will quickly replace it if the price rises too much.
Power lines are already aluminium. Even though it is less conductive, the light weight means the thickness of the aluminium conductor can increase to accomodate higher current levels.
