Uh, no shit? That's how light works once you're able to travel at relativistic speeds - communication over interstellar distances using light is going to take ages.
Even within our own solar system interplanetary travel will have significant communication time delays.
Edit: also, we already know that matter and light can't exceed c, but I wouldn't be surprised if we discover that other forces (gravitation, or another that we haven't understood yet) can transmit information at speeds >c. I wouldn't be surprised if we turned to quantum entanglement for instantaneous communication over extreme distances either.