Saying that the days of Noah means having Nephilim around is bad exegesis (analysis of the text). It could very well mean an immoral, self sufficient society who couldn't care less about God's warnings...exactly what we have today.
On the other hand, it seems that modern Nephlim could be "walk-ins" , demon possesed people (humans who played too much with the occult) who are more and more abundant these days. It seems they will be the back bone, the SS troops of the antiChrist.
You have a right to this opinion, but the phrase bad exegesis is uncalled for. I do not intend to argue this point, but let the reader of Genesis study this for himself. The Nephilim will come again with their leader and how this will occur and be presented to people will be very modern indeed. I have decided not to go further with this topic. I respect your opinion and will end my comments on this truly grave matter.