'TIE Fighter' story speculation: What if Zaarin's plan succeeded? (Spoilers for TIE Fighter)

Okay! I've recently been playing TIE Fighter and I'm loving it. Excellent space sim, and I love playing for the Empire - such glee as I blast the rebel scum out of the sky!

Anyways, I'd like to open up a discussion and speculation on an aspect of a storyline of TIE Fighter. Now, ahead of this sentence are heavy spoilers for the latter stages of the game. If you haven't played it and wish to remain unspoiled, feel free to drop out of this thread

As we who have beaten or spoiled the game for ourselves know, Zaarin launches a coup attempt against Palpatine. He captures him and intends to have him executed and thus seat himself on the throne and rule the Empire. However, could he have pulled it off, even *if* he killed Palpatine? One question we need to ask is how he would have secured the loyalty of the Imperial Navy, which he would have absolutely needed to hold power. I mean, how would he have even accomplished this with Darth Vader on the scene and at large, which EVERY IMPERIAL OFFICER KNOWS is Palpatine's direct second-in-command (not to mention how every intelligent Imperial officer is *terrified* of Vader and would likely support him for that reason alone).
Secondly, in the mission, Thrawn shows up before Zaarin can get Palpatine's shuttle onboard his ship. Now, let's change the storyline a bit and have Zaarin hurry things up and get Palpatine on his ship and have him killed right before Thrawn arrives. Thrawn has still arrived, and thus still outmatches Zaarin. Plus, Darth Vader is still on the scene. So I'm thinking that the best case scenario for Zaarin is to kill Palpatine - period. That's it. A political assassination. In the wake of this, Zaarin's uprising is crushed and Darth Vader is put on the throne as he's the next-in-line in Palpatine's command structure. But THIS raises a number of interesting questions which we can also discuss - how would the Empire have fared under Vader? Would he have been more or less brutal, more or less competent than Palpatine? Would the Rebellion have a greater or lesser chance of success under him? And more importantly, how would Luke's attempts to redeem his father play into this if his father IS the Emperor?

Anyways, I'm totally open to discussing alternate perspectives on what would have happened if a) Zaarin's plan had succeeded, and b) Zaarin ended up killing Palpatine, but failed, and Vader ends up on the throne.

Let's get to it!

 

I do not think Vader is political figure. Pestage would probably still be the Emperor after Palpatine died.