Just like a video game which hass been given the latest updates, Tesla vehicles which feature the Hardware 2.0 format will get the latest functionality form of high speed Autosteer. The expected rollout date should be in the next 2 weeks, but no official date stamp has been put on the complete updates.
The company don't usually put an exact date on their releases saying that its simply ready when it's ready, as rushing through a release like this one could be dangerous. A recent Tweet gave away the headline.
@elonmusk Things have been too quiet on the HW2.0 AutoPilot features. Any idea when we can expect an OTA on it?— Adrian A. Volts (@adrianvolts) February 24, 2017
Those lucky enough to have squeezed in the Hardware 2.0 to their Tesla purchase should expect constant updates throughout the year which will continue to improve the functionality of the vehicle, which should end up with full autonomous driving. All Tesla vehicles sold as of now will feature Hardware 2.0 and the upcoming Model 3 will be capable of autonomous driving out of the box.
It also seems that as of the update of 2.48.16 current Auto steer is now limited to the speed limit of unsurfaced roads as per this Tesla forum thread, which seems to be more of a safety precaution. Auto steer is not technically designed for those road surfaces. This shows that Tesla are slowly drip feeding these updates and gaining as much raw data as possible to make the functionality safe and roadworthy.
Therefore, those eagerly anticipating the Autosteer functionality should at least wait a few more weeks before the update kicks in everywhere. Like all software updates the two-week timeframe is a rough estimate.