Except, again looking at Star Wars/A New Hope, they mention an Old Republic. What happened to that Old Republic? Why is there a senate to be dissolved if this Republic has been gone for so long? Is the Empire new? How’s it gain so much power so quickly?
Snoke doesn’t undo anything of the original trilogy. Palpatine not being defeated does, but a new threat coming from the Unknown Regions does not.
It’s not any more or less established in universe, your need for every answer coming from a 30 year gap is not the same as a flaw in storytelling.
Imagine in Episode V’s crawl opened with the New Republic many years after the defeat of the Empire. It wouldn’t make any sense and would make ANH feel pointless in retrospect.
I mean… Until a sequel was announced, most people just kind of assumed that the Death Star getting destroyed meant the Empire was gone too. They put all their eggs in one basket, banking on this Death Star thing so hard they dissolved the Senate that was so critical to their control of the galaxy, and it all fell apart.
If Star Wars 2 had such a wildly different setting I don’t think it would have worked, but not because the setting doesn’t make sense.