Student or Learner
Robots will probably never replace humans. Wouldn't it be nice, though, to have companions who will do our drudgery for us?
Why "wouldn't"? It refers to future.
What would be nice is having companions who will do our drudgery for us. There's no suggestion that the speaker is claiming that it's nice just thinking about that.
If you were correct, the speaker would say "Isn't is nice imagining that ..." not "Wouldn't it be nice ..."
"Wouldn't it be nice ..." is conditional, and the condition hasn't been met yet.
As the original poster rightly says, it refers to the future.