Is the word 'illusory' used in the same way?
No, illusory does not have any positive/negative meaning for me. I don't think it fits your sentence, so I will wander off topic by suggesting that you might perhaps rewrite it.
'Quite the contrary, neo-liberalism has prevailed all over the world, and therefore it seems that
there is now no realistic prospect of the emergence of an ecofascist regime controlled by ecocentric communitarians, after the triumph of a green party in a general election
, is only a pipe dream.'
However, that is a very long sentence for an oral presentation, so I suggest that you reconsider how you intend to make your point.
I can't make any more suggestions - that would go way off topic for
pipe dream, and we don't proof read here.