Now sure, the Galaxy Class ship will be hopelessly outclassed, and the Victory will be the most powerful vessel in the entire galaxy.
Hardly. There are good arguments for a Galaxy Class ship being the most powerful ship in the new galaxy it finds itself in, and the Star Destroyer finding itself distinctly outclassed. However, leaving that aside for another debate...
Should be insightful, perhaps you should start a new thread on the matter.
I think that the assumption that the Star Destroyer will be able to generate spare parts does not stand up because they do not have anything like replicator technology as in Star Trek TNG onwards.
Yes, they do
They're called Duplicators and they function nearly the same way as Trek Replicators
In order to be able to keep going they will have to rely on trade. But they do have something very trade worthy which is hyperdrive technology which does not exist in the Trekian galaxy.
So I think that they will settle down to a very successful and lucrative career in the Milky Way selling hyperdrive technology. The implications of this will be an enormous increase in the ability to travel across the Milky Way which would lead either to an era of unparalleled increase in trade or conflict. Either way, no one would forget their impact which would change the Milky Way for ever.
Optimistic and possibly the approach a Victory Class in Republic colors would take, Overall it's more likely they'd use the ship's tactical and strategic superiority to subjugate a small empire and expand ever outward (like the Son'a), the VSD would guarantee victory and serve as deterrent until a fleet can be outfitted with turbolaser/shield/hyperdrive tech. Once that happens nothing will stop the "[inset name of Star Destroyer] Empire."
I do not think it will work out so well for the Star Ship. They would carry on doing what Star Fleet does and explore the new galaxy while working on a way to return home, a la Voyager. They will be able to generate spare parts using their replicators, so could keep going a lot longer. But, in a galaxy dominated by the Empire I think that they would attract attention before too long and the Empire would want to gain access to their warp drive technology which does not exist in the Warsian galaxy.
First off, you don't need to add -ian, "Trek galaxy" and "Wars galaxy" are sufficient, if you find Milky Way and GFFA are too clunky.
Secondly the Empire wouldn't have much interest, a GCS is a snail compared to Wars ships (it takes 70 years for a Trek ship to cross a quadrant, a Wars Civilian freighter can cross an entire galaxy in days,) if the Empire had any interest they can with ease intercept it.
Even if we disregard the FTL disparity, Imperator Class Star Destroyers (the 25,000 ship strong core of the Imperial fleet) sublight max acceleration is 2,300G, and Super Star Destroyers (i.e. Vader's 17.6km long flagship) sublight max at 1,250G. The Galaxy Class has a design goal
sublight max of 1,000G.
If the Empire really wants it (God knows why), only auto-destruct can stop them.
A Star Fleet captain could not agree to share this technology with a regime such as the Empire, so the Imperial Fleet would try to take it.
The Empire is very good at putting on a good face to outsiders, only the Rebellion and its sympathizers are fully aware of the evil. Since the Empire is a Galaxy spanning civilization the Prime directive doesn't apply (consequently if they meet the Empire first the PD would disincline them from helping the Rebellion, since the Galactic Civil War is "by definition an internal matter of the Empire.")
Given the situation, the Feds would trade everything not bolted to the hull for a used hyperdrive and enough credits to start a plucky one ship transport business. The Wars galaxy revolves on money, outside the outer rim trade alone won't get you very far.