Sean Mitchell makes the case in a video that Tesla has advantages to standardize on the 2170 battery cells
If Tesla moves to 2170 cells for S and X, it should by nature of the battery architecture be able to withstand an upgrade from 120 kW charge rate to something higher.
In late 2018, Elon Musk said Tesla has a new battery (pack) design. It will be lighter, better, cheaper and will be introducing that around the end of 2018. It will volume production in the first quarter of 2019. It will make the cars lighter, better, and cheaper and achieve a higher range.