ip v6 are used here and there, mainly its being wrapped in ip v4 so really it makes no diff, as for ip v6 that protocol has its own shitloads of issues, mainly that privacy might be a thing of the past as governments introduce more and more invasive laws due to "THE TERROR THREAT" and that IP V6 theoretically means an invidual, unique IP for every netenabled gizmo...
Mind you, lets see if ip v 6 ever gets off the ground before v7, v8...
Also, the ipv4 shortage COULD be resolved fairly easy by releasing alot of the IPS that are currently reserved.. and more wise use NAT will do its bit too(as it already has)