Will falling battery prices change the grid

With the official anouncement of the gigafactory, Tesla says there costs will drop 30%. Many think teslas cost is around $250/kwh now, which means a drop to $175/kwh by 2018. If the market in the US is around 1 million 10kwh+ cars in 2020, then in 2030 there should be plenty of used batteries available to the grid at much less than $100/kwh.

The grid changes slowly, but already in texas wind makes up 10% of electricity. During the summer it is quite valuable to shift electricity, and some wind is wasted because of grid congestion. In hawaii, with electricity coming from coal and being expensive, More solar may mean more batteries make sense. In europe, germany and denmark could really use batteries to manage the wind and grid congestion.

Thse places don't have good resources for pumped storage. Other possible grid buffers are converting excess electricity to hydrogen and using it in fuel cells, and creating air compression storage. Less expensive batteries may be a great buffer for small changes, with fuel cells/hydrogen handling bigger fluctuations. DOE has pilot programs for all of these.

Since coal and nuclear plants are built for 50 years, the possibility of battery backed wind should kill new coal and nuclear plants where the government does not heaily subsidize them and it has good wind potential. They may still be viable in places without acceess to good solar and wind. Less expensive batteries and PV pannels will also make solar thermal less viable.

What do you think, will plug-ins lead to synergies with more renewables? Or is the politics of the grid so screwed up that legislation is needed?