Gallia is not dying a slow and rotting death. The Gallic Royal Navy, the Gallic faction that has the most zeal towards isolationism, has new members daily. They have a lot of fun, despite the frustration we often receive from traders and explorers who haven't made the effort to understand the situation of Gallia and decide to abuse it in one form or another.
Your prediction is horribly wrong. We will never die out, because there will always be that trader that is going to abuse the Gallic trade lanes and attempt to make a profit. There will always be that explorer that is looking for a thrill and dares defy our warnings. There is always something to do. It doesn't matter how many people will shoot; they will not stop. But then again, neither will we. And you may say "See, you need those people!" then you are still wrong; I would actually trade one hundred of those people for a decent Council player (not that I'm saying current Council players are horrible... we just need more of you!) And when Gallia is empty, I have no problem training against the battleship patrols that clash constantly in the contested systems. THAT'S interesting.
I have been playing in Gallia since the beta. The majority of my characters are Gallian. I have not grown bored yet. Why? How can I? The systems are beautiful and the lore is intriguing. I'm very excited for .86. These current Border Worlds are just the tip of the iceburg... I can't wait to see the rest of Gallia.
Following what Tybalt said, Gallia is only as interesting as the players make it. The GRN have made it pretty interesting for one side of the war, and kudos to a developing Maquis faction that has done a good job setting up so far. There is nothing wrong with Gallia; it might not be for everyone, and if it is not for you, don't flame it.
And to those who don't believe Gallia would be still in existence after 800 years of isolation, who believe they would not have superior technology and numbers, and who do not believe they would retain a grudge for centuries: Read. The. Damn. Wiki.