Or may be we can call it intergalactic financial system as we don't need to send anything physical but the information. And studying about quantum entanglement, it is clear that the information can travel faster then light so it can become a system among planets, solar systems or even galaxies. But first we have to find if really someone is out there to receive them
Even if we get to send things at the speed of light, it will still take years if the distance is lightyears away, unless we have portals or wormholes to create a shortcut, there's no point hyping bitcoin as a money for interstellar civilization, bitcoin and technology has it's own limits.