Yes, anything with NXT but no public key should be totalled. Maybe the page would list all dark accounts, with the sum at top and below it a list of all the accounts and their balances?
I guess we're going with the term "darkNXT"? I kinda like hiberNXT or frozeNXT
adding tomorrow, hiberNXT sounds supple.
I'll call it hiberNXT in my client then. (Though I don't agree with the assumptions being made about what it means when there are no outgoing transactions on an account.)