Most probably never. Early 2016 models are based on the BRAVIA 2015 (ATV1) platform. Rumor has it that after Nougat (which has been released in the U.S. and did not contain Google Assistant or Amazon Alexa) there won't be anymore major updates. So no Oreo and no decent voice assistant.
Cheap XD70/XD80 on the other hand got those features. As they have been released 3-4 months later compared to XD85/XD93/XD94, those are already based on the ATV2 platform. Total mismanagement if you ask me...
