That is a rather optimistic projection of the rollout of Level 5 autonomy. The total number of heavy trucks sold worldwide was less than 400k in 2014, and no one has full Level 5 yet (if it can even be done large scale at a profit), so I would adjust those expectations. Most 'displaced' truckers should be able to find work unloading automated long-hauls into smaller short-hauls and driving them during a lengthy transition period.
> your only options are to find a system where people have value independent of their productivity, make being valueless palatable, or just go die quietly
Points 1 & 2 are somewhat interconnected. If I add up the retail value of all my non-paid work, it comes to far more than I make at my day job, and I suspect this is true for many others. Much of what our culture calls "valueless" - because no money is involved - does actually have value, and this will become more clear as time continues to reveal how difficult automating everything really is.
We have already seen this, for example, with people posting what used to be called home videos (no revenue) to YouTube and stumbling into large amounts of ad income, and I believe we'll see it in more areas. It may increasingly be a 'gig economy', but it's happening slowly, and some of those gigs are turning out to be pretty good.