The dark forest is conditional on that it does not require huge amounts of resources to eradicate another civilization and that (over time) the universe turns out not to be of a scale enormous enough (and in the book there are agents working to actively make it smaller).

Bringing it back to the dark forest of idea space, it is an interesting question whether the the space of feasibly executable ideas being small (as this essay assumes) is inherently true, or more of a function of our inability to navigate/travel it very well.

If the former, then yes it probably is/will be a dark forest. If the latter, then I would think the jury is still out.