If you truely believe that transition to 64bit coordinate system in star citizen was made because to sell more ships (see how fast I learned to cope with the rules here!) than this is consistent with the source of your information.
There's no info the 64bit coordinate system in SC has anything to do with the layout of the star systems in the galaxy, but we do know it was introduced to provide a seamless transition in the "one" existing system, and the reason we know that is because that's what they told us it was for!
One of the greatest challenges in getting Star Citizen working in the first place as a massively multiplayer game is due to the nature of its scale. In a typical game, you have dedicated levels or dedicated open worlds of limited size. Star Citizen operates on an entirely different level of magnitude - and to enable this, the developers converted the engine to use 64-bit coordinates to enable solar system-sized game spaces - 536,870,912 times larger than a space based on 32-bit float coordinates.
This of course tells us nothing about other systems apart from the fact that they also will use 64bit coordinates inside the system. If you think you need 64bit coordinate systems to represent the location of 100 star systems I have news for you, and it's not good! It's very likely SC will simply use a loading system based on a wormhole minigame for each solar system and not bother with 3D galactic coordinates because there's very little point. Now I am not saying that's a bad thing for a game with only 100 systems, I mean why bother with a 64bit coordinate system, it's not necessary on that scale, it's just we don't know how they are going to do it.