As I understand the Rebellion was formed to overthrow the Empire and replace it with a Democratic government. According to http://starwars.wikia.com/wiki/Yuuzhan_Vong the Emperor was aware of the presence of a massive invasion force of extra-galactic Yuuzhan Vong after a scouting mission was intercepted by the Aliens.
That was supposedly his real justification for opening hundreds of cloning facilities and recruitment facilities as well as further industrializing the Empire. After the Rebellion overthrew the Empire the Galaxy was sent into an economic depression and was plagued by war. This made it relatively easy for the Yuuzhan Vong to conquer most of the Galaxy for a time.
My question is: Would the Empire have been able to stop or at least hold at bay the Vong long enough to work out a treaty? If this was to occur, how could it have affected the galaxy for the better or worse?