The improvements will likely add a few dozen additional miles of range. There is no specific target date for the upgrade, but the general expectation is for the second half of 2019.
Autopilot Software Upgrade

Tesla has upgraded the Autopilot where drivers no longer need to confirm lane changes. There are now three options for Autopilot notifications and confirmations – 1. Enable at Start of Every Trip Through the Enable at Start of Every Trip setting, Navigate on Autopilot can be set to automatically turn on each time a driver enters a navigation route. Once enabled, anytime a driver is on a highway and uses Autopilot with a location plugged into the navigation bar, the feature will be on by default. 2. Require Lane Change Confirmation If a driver selects 'No' to Require Lane Change Confirmation, lane changes will happen automatically, without requiring a driver to confirm them first. 3. Lane Change Notification. Drivers can elect to get notified about an upcoming lane change by receiving an audible chime as well as a default visual prompt.
SOURCES – Tesla, Electrek