Technically we don’t know at the end of ROTJ that the Empire has fallen or that there will be a New Republic. That’s actually established in the crawl of TFA.
But that’s a good assumption to make, based on the celebratory atmosphere on multiple planets, including the capitol world.
Come on. That’s special edition talk!
He’s got you there. Get outta here!
The EU says that the Empire massacred all those people partying on Coruscant anyway. 😛