A question though (also : are neutron stars potential predecessors of black holes or do black holes only come from even more massive stars collapsing ?) but the question as i'm in interview mode for a second after reading this;

You need much bigger stars to start with to get a black hole instead of a neutron star. So in other words, they are not predecessors of each other.

I don't have any thoughts on the paper you are referring too (that is available from here). It seems like a new idea about dark matter (that appeared at the very first moment of the universe history) that is very valid and will be testable in a few years. I however do not understand the pre-big-bang statement as the two examples of the introduction refer to cosmic inflation and dark matter freeze-in that occurs after the big bang... I will read it more closely after my return from vacation :)