Dark matter and black holes have nothing to do with one-another. Even in your linked article, Dr. Hawking is not arguing that black holes don't exist; just that

Dark matter and black holes have nothing to do with one-another. Even in your linked article, Dr. Hawking is not arguing that black holes don't exist; just that their properties may be quite different from that which they are widely expected to be. There is very little reason to doubt, and in fact there is enormous observational evidence to support, that there exist (and yes, that we have discovered) bodies in space whose mass is contained entirely within their Schwarzschild radii.