It’s a broad side of the trailer which is a challenge. Tesla will stop for the rear-end of a trailer, but may disregard the broad side of a trailer stretching across the highway because it looks too much like an overpass.

Definitely corner cases like the broad side of a tractor trailer stretched across the highway will prevent FSD from being remotely possible in 2020. Complex traffic light arrangements in multi-lane intersections, unprotected left turns, even driving over a lane marker to avoid a fixed obstacle are still TBD features in the AutoPilot code base.

Those are the features they will be adding in 2019/2020 to get what Musk is calling “feature complete” but regardless of what he has claimed, from personal experience, I do not see how the cars could operate without any human driver in 2020 except under highly constrained conditions like “in parking lot not to exceed 3mph” and even that I think will expose corner cases with cars getting stuck and needing driver assistance.

What I do think we will see in 2020 is a respectable percentage of trips being completed start-to-finish with AutoPilot engaged the entire time.

However, then and now, the driver absolutely, positively, must always be looking out the window when operating AutoPilot.