For the foreseeable future I would imagine the currency is decentralized. The C-Bill may come back because I doubt the Kerensky-bill (or Sea Fox currency) will truly catch on.
It's likely that the Star League dollar will come back if Star League is fully reestablished.
Work Credits like Kerenskies are internal currency.
Sea Fox Credit would likely be leading candidate for true interstellar currency.
It's up to writers and developers want to do.
Sea Fox Credit as it stands, especially as their running the old Mercenary Review Board in name, it gives more power/credablity to their currency.