What I would like to do is rationalize the past of 2300Ad with our present and future. I have trouble seeing something like the Twilight War given the present circumstances. So, something has to unbalance the equation.
The Twilight War gave 2300AD a divided Germany, superpower France, isolationist America, a huge population die-off, and an excuse for the retarded (as in slowed) state of technological advance. To get to the end state of 2300AD, we would need something similar.
The reason I like an asteroid as a war starter (or ender) is that it provides an additional excuse for the skewed nature of 2300AD technology. An asteroid impact would have served as a strong goad to get back into space, both for early-warning/defense, and a get-our-eggs-into-more-than-one-basket sort of deal. After Twilight, there would be very limited resources for scientific and technological development. An emphasis on space technology means that less attention is given to computers, or consumer electronics, or AI research. The development of the stutterwarp merely accelerates this, and adds the challenges of planetary colonization and terraforming to the mix.
Instead of a divided Germany, perhaps we see a divided EU, with Germany broken into rump Germany, and a French client state called Bavaria, which includes southern Germany and Austria. The War of German Reunification becomes the European Union war, where the small nations of Europe unify against French protests. The actual War itself is more of a demonstration of force sort of thing, with few casualties.