This thing has always puzzled me. The entire cycle of revenge began with the failed Naga Sadow invasion of the Republic, Sadow was always in favor of the Empire's expansion. On the other hand, we had Ludo Kressh who was against the invasion and believed that the Empire should dig in and wait for a possible invasion, but most of all, not to invade the Republic because it would destroy the Empire, and in the end it happened, the Courts did an operation under a false flag that the republic is invading and must be answered. So the question is what would happen if Ludo's option won
A good question. Probably the Sith Empire lasts a bit longer, though its stagnation while being built on a philosophy of ambition and opportunism might bring about a destructive civil war almost as quickly. And war with the Republic might still come at a later date - after all, Kressh's isolationism was of the paranoid kind rather than hoping for peaceful coexistence, so either the sith create diplomatic incidents by killing republic ambassadors and explorers or someone else follows the path of Naga Sadow and decides a preemptive strike is the only option.
Would be interesting if there would have been a diplomatic relationship between the Old Republic/the Jedi and the Sith Empire in this case and what it would have been like. If there wasn't a Sith civil war or an invasion of the Republic
With Sadow's paranoia and chauvinism, I think his priority would have been to protect Sith space from any further incursions -- so I can see a military buildup for defense purposes, but also supercharged research and experimentation with various forms of Sith alchemy and sorcery in order to create traps, misdirections and a staggered array of unexpected weapons to deploy against whoever dares approach. The optimal outcome from Kressh's point of view, I guess, would be for everyone out there to consider Sith space a cursed place that is better avoided -- though rival factions and parts of the newly-expanded fleet would probably come up with expansionist / preemptive-strike plots every once in a while. ("We have all of this power now, why not use it?" is a not-uncommon motivation for war, sadly.) Perhaps Kressh's son would eventually be the one to oust him and strike out, after spending his youth coddled and stifled by his overprotective father.
Imagine a Sith Empire that is not in conflict with the Republic and Jedi, and another threat (Vong or other) attacks the Jedi and Republic and they come to help, winning big favors and even if Jedi mistrust them, loose the Republic's trust to the Sith's effectiveness?
Now i would like to see at least some fanfiction with the Sith Empire, having survived because of Ludo Kresh, and eventually either peacefully merging with or joining the Republic. Wonder what their relationship with the Jedi would become like, after centuries and millennia of such a union.