I don't believe quantum computers will ever deliver. One-time- pads aren't really a solution either. There are two problems: How do you produce them and how do you deliver them?
The beauty of public key encryption is that anyone can send you an encrypted message that only you can decrypt. The public key is the product of two very large primes and the algorithm is such that that you need the individual primes, the private key, to decode the message. The security of the algorithm relies on the difficulty of finding those primes.
Up to present, as far as I know, quantum computers haven't yet succeeded in finding the prime factors of numbers with more than three digits. There is still a long way to go. As I understand Shor's algorithm, they aren't likely to ever get there. I believe the limits of Shor's algorithm are about the same as our ability to measure time or frequency, with goes to 18 digits or so, a far cry from the 512+ digits required to attack current public key algorithms by that approach.
Historically, it has always been far easier to capture the sender or addressee and menace/torture him a bit.
Jeroen Belleman