When you say goodbye does it kill the hope of meeting again?

Not necessarily, though it depends on how you use it, in what situation you use it, and the words around it that you use in the sentence, or previous sentences.

If your saying it to someone you don't like for instance, and they know you don't like them, they will get the message.

If you are saying it to someone you like, as a friend or etc, they know your basically saying: "See ya later."

Though if your saying it to someone you do like, I'd recommenced saying: "See you later," or "See you Tomorrow," or "See you around."

Those open up the chances for meeting again for certain.

Or you could just not say goodbye. Kills the chance of you meeting again.