Good theory but this is what works against it .
If harry was one of the horcrux, Voldermort wouldnt have tried to kill him at every opportunity. In the half blood prince too , he tried to kill Harry and so I dont think he is one of the horcrux.
In my opinion, one of the horcrux would def be a person and it might be someone who is dear and close to Harry, however I dont think its ron or hermione.
Somehow I think neville might play a major role in all this, he is connected to all of it.
Hagrid might be the person who dies , the other person has to be Snape.
I dont think they would kill harry, ginny, ron and hermione coz its the last book and somehow she would try to end it on a happy note.