Is a dystopian future plausible?

It's plausible because human-kind has experienced 'dystopian' moments throughout history. http://dictionary.reference.com/browse/dystopian (a society characterized by human misery, as squalor, oppression, disease, and overcrowding).

Adding the "Big Brother" concept to the mix is simply increasing the proficiency of what most societies have had a semblance in place at various times and sometimes with great consistency. i.e.; British Monarchy attempting to stay 'on top' of the American colonists, small town perspective ~ knowing other peoples business, oppressive religious leaders and advocates keeping the "faithful" under their thumb via abusing knowledge and coercion. The examples would be potentially endless.

Addressing the "Big Brother" perspective further, who knows whether or not we have already been living 'under' such a situation for some now? Would it make sense for those behind such a controling approach to be blantant and reveal what is actually taking place? I think not. Yet could easily be wrong.