They don't even need to deal with the subspace part. Beams will go straight through the shielding, and the Colossus, two cruisers, and a corvette will make short work of the FS1 Lucifer, so...
The NTF would never have exsisted, as Aken Bosch would never have had the experiences he did with Shivan technology during the Hades rebellion. The Hades might have been completed, and the coup might have been launched...only to have the Hades hunted down by the Colossus and other beam-armed ships, which would have blown GTVI's superdestroyer to metallic confetti.
It might not even have gotten that far: the fleet would have known of the GTI rebellion, and would likely have moved to stop it before it could start...and perhaps profit from it by having the forces available to storm the Jotenheim installation, seize the GTI labs, and then find and storm the site where the Hades was being built before the superdestroyer was anywhere near functional. What GTI knew of the Shivans they would not have been able to take to their graves this time around.
The Second Shivan Invasion would never occur. The GTVA would have formed much earlier: there's nothing in the arsenal of the GTA or PVN at that time that could've stopped the Colossus and its fighters. The fleet could simply dictate the formation of the GTVA to the GTA and PVE.
The PVE might remain, or it might become the Imperium. It's unclear how much of the momentum behind the change of government for Vasuda was the result of the Terran-Vasudan War and how much was the result of the devestation of the Great War. That can't be accurately predicted.
The GTA would probably have gone into the GTVA as a whole, and post-Great War skirimishes between members would not have occurred...or would have been promptly squashed by the Colossus.
