The dementors are on Voldermort's side so they will not be the ones to kill him besides if anything were anticlimatic that would be it Harry has got to be the one to finish it or it would just be plain rediculous

When Voldermort was reborn from Harry's blood he was able to touch him unlike in their earlier conflict in the sorcerer's stone but the love he has in him as not from his mother's spell but how he chose to be is what causes voldermort pain from their connection

Finally I think you guys might be over thinking it with the wand cores of ron and hermoine's but the connection between the pheonix feathers shared by both Harry and voldermort was already shown in the graveyard in goblet of fire