This is the necessary link between the premises and the conclusion. If this were not true — if plays could be popular centuries from now even if they weren’t regularly performed — then the premises wouldn’t prove that the plays won’t be popular centuries from now.

The author’s reasoning has nothing to do with critical acclaim. The author mentioned critical acclaim in the beginning, but that was simply part of context and plays no role in the premise to conclusion structure of the author’s argument.

Not necessary, because the critic doesn’t have to have seen or read all the plays. We know as a premise that none of the plays written last year examine human nature in a skillful way. The critic doesn’t need to have seen or read all plays in order for that premise to be true.

The author’s reasoning has nothing to do with critical acclaim. The author mentioned critical acclaim in the beginning, but that was simply part of context and plays no role in the premise to conclusion structure of the author’s argument.

The author’s argument concerns plays that do NOT skillfully examine human nature and what will happen to them. So the author doesn’t need to assume anything about what will happen to plays that DO skillfully examine human nature.