Q1 typically has lower revenue from vehicle deliveries, so if Tesla wants to boost their Q1 numbers, recognizing deferred revenue seems like a reasonable alternative especially with over $1 billion (not necessarily all FSD related) according to their FY2019 update.
Unclear if FSD visualization preview counts as a feature for recognizing some revenue. For 2019Q3 -> Q4 the total deferred revenue still increased although this was limited to just US market. If some revenue could be recognized, making the visualization available to the rest of world seems like an "easy" change (even if the visualizations are not quite right as seen in the existing US behavior).
"Reverse summon" (i.e., "park seek mode" ??) was recently mentioned, so that definitely would be a feature allowing recognition of revenue. Zachary Kirkhorn said Tesla was able to recognize $30 million of deferred revenue when Smart Summon was released in the US, so one would guess a similar proportion could be recognized with the "reverse."
And as always, there's stopping for traffic lights and stop signs and navigating through intersections for "feature complete."
Any other hints at what "FSD features later this month" might be referring to?