As-Salamu `Alaykum Wa Rahmatullahi Wa Barakatuh akhi,
There is something miraculous about this as his (may Almighty Allah bless him and grant him peace) prediction came true; that is, there are currently either 72 or 73 sects of Muslims. Almighty Allah knows best, but I think this Hadith means that one sect (the one that follows his Sunnah) will be fully correct whereas others will have lots of Bid`ah (innovations in religion) in them. I don't think it means each and every person of those sects will go to Hell, because if Almigthy Allah willed, He could rescue those with sincere intentions. But of course and without a doubt, the proper sect is the original sect of Islam; that is to say, that following the Glorious Qur'an and the Sunnah of the Beloved Prophet (may Almighty Allah bless him and grant him peace) and is free of any kinds of Bid`ah (innovations in religion). As I said, Almighty Allah knows best and I am no scholar.