But delivery trucks will still need someone in them to make the deliveries. But what would change is that the delivery person could be doing things in the truck while on the rounds - this could be related or unrelated work.
Generally, if a technology transition releases a lot of productivity, it also drastically lowers cost of whatever is affected (delivered goods, which is everything). This, by rights, should free up a lot of extra money for people, which they can then spend on other things. The other things generally cause more economic activity somewhere else, which should create the new jobs.
But a portion of truck drivers will lose their job, with it never to return.
However, this can't be, nor should it be, stopped.