But the Empire and the New Republic had parity. Han even says in the Thrawn Trilogy's beginning that both the New Republic and Empire were at equal strength, and the former fought harder. The Empire didn't snuff out the New Rpeublic/Galactic Alliance until 130 years after the first movie.
It's honestly been a long ass time since I read the books, but my understanding is that in Zahn trilogy the New Republic were in 'clean up' mode with the Imperials, more or less having run down most of the warlords and splinter groups that came in the wake of the Emperor's death, with the arrival of Thrawn being what galvanizes the last of the Imperials for a last gasp push. This was like ~5-6 years after RoTJ.
Suddenly, you have an Imperial threat that is kicking the shit out of the New Republic -- Coruscant is under siege and cut off from everyone, Thrawn is conquering planets, the Imperials suddenly have a bottomless supply of troops again, etc. But these are all built up and they're made into credible threats through the story.
This is what I mean by Disney doing shit really fucking stupidly -- the New Order in Disney Wars are suddenly this mega juggernaut with endless resources because the script demands that the heroes have a credible threat. Shit just springs forth malformed and poorly thought out because the script requires it.
The end result is the same in both the EU and Disney Wars -- the good guys win, the bad guys suffer another setback, but one left an impression on fans and was well received while the other was a wet fart.
Er, no. Not even with the EU. The Jedi return for good, which means ROTJ's ending sticks. In fact, when the Empire crushes the Alliance, it turns into a messy war over the Empire's throne, with a Jedi faction and a Sith faction having equal power and sending armies of Stormtroopers and Star Destroyers against each other.
I'm looking at shorter story arcs where the Empire are built up as credible threats (which is why I was referring specifically to the Zahn EU trilogy and not the entire body of EU), similar to how they were in the Sequels, rather than the entirety of the EU put together (which, again, lol when they get to late stage EU.)
You really think that if they explore post-sequel Star Wars there aren't going to be Jedi?
That has already begun. The new Thrawn storyline is practically Heir to the Empire; they even name-drop it.
RLM whined that they don't care about the books. Well, the books are now the future of the franchise.
I mean, they've been doing it almost nonstop.
The aforementioned cribbing of Dark Empire.
The shit with Boba Fett coming out and working with other bounty hunters is similar to the Boba Fett books when he escaped the sarlacc.
There's the shit with cortosis ore and the Dark Trooper project in the Mandalorian. Plus the dark saber.
There was the Dathomir witches in the Acolyte.
Thrawn in Ashoka.
The (rumored) scrapped Rogue Squadron project.
But it's never done (IMO) in a satisfactory manner and always has that Disney spin on it to make it shit in some way.