Battery question - upgrade available after manufacture?

Battery question - upgrade available after manufacture?

Has there been some indication of whether it is possible to add the additional cells after production that would increase range from the base 160miles to 230miles?

The reason I ask is it is possible that during the lifetime of the S my driving habits may change. So hypothetically one could ask for range extension. If the upcharge is $10k from 160mile to 230mile range at manufacturer could Tesla charge something like $12,500 for an upgrade a few years after ownership at a Tesla shop?

I'm making a huge assumption that the size of a smaller range battery is less therefore making it possible to add more battery capacity.

Sorry if this question has been asked to death - I couldn't find it using the 'Google search' method. For all the forums I visit I must admit this is the first without a built in search tool.