I do not want to be un-constructive, but I must point out the obvious. This has been done before every which way. There are numerous custom campaigns for SC/BW alone depicting a hypothetical Brood War 2, such as HunCraft, War of the Tribes, The Fenix, Palinchron Concordance, Recolonize Mar Sara, After Brood War, Dark Cold, Final Chapter, Praetor Daexan, The Hybrids, The Hybrids Chronicles, The Revengers, Ascension of Duran, The Last Cerebrate, Empire Wars, Uprising and Resurgence. Enumerate outlines a detailed yet flexible alternate timeline in fourteen pages, and over a hundred pages on concepts for technology and culture, which prunes extraneous elements (e.g. QoB, Duran, UED) to focus on the original premise of the franchise.
Why would you want to reinvent the wheel as opposed to adopting a previous wheel? What makes your attempt stand out from the many others that came before? I do not think your idea is bad, but I wonder if you are going off half-cocked and I speak from experience when I say that. I spent many pages on notes for my version of Brood War 2 and alternate timelines, but after I learned of all the successful campaigns and documents that already came before me I gave up on reinventing the wheel and just attached myself to what already existed. There was no point for me to continue my notes because the previous works had already come to the same conclusions independently. The best that I can do differently is to integrate obscure concepts and stories from the canon expanded universe and devise possible story hooks based on the materials I have at hand.