No the vampires are just another unresolved plot thread. Instead of actually providing us with answers as to what the hell the gantz is the author has just created another pointless story arc which is leading the series in a completly different direction and it will most likely not bring any kind of answers as to what the hell the gantz is and what it's purpose is.

The only thing we've been promised is some sort of cool showdown between Kurono and his little brother. Honestly I could care less about that and I would rather see some sort of explantion as to what the hell the gantz is.