We also know they took the whole "Kerrigan gets de-infested and leaves with Raynor" plot line from a few fan campaigns. Duran being a Xel'Naga shapeshifter, as well. But yeah, we already know about these. I wish Blizzard's story team would've surprised us more when it comes to SC2's story instead of catering to expectations and rehashing fan ideas.
Blizzard has never been good at writing. With the benefit of hindsight, it is clear that they were making up the plot of SC on the fly. Notice how every campaign systematically destroys all the world building painstakingly setup by the previous installment?
SC2 had nowhere to go but down because SC1 had an unstable plot to begin with due to a tumultuous development history. Making Mengsk, Raynor and Kerry the main characters to the exclusion of other more interesting plot threads (or the logistics of the setting itself) proved to be detrimental to the story. Systematically destroying and retconning the cultures of all three sides proved detrimental to the story.
Because the constant setting turnover and absurd retcons, it is impossible to continue the story of Koprulu in a way that does not feel artificial, forced and ham-fisted. The three sides having their motivations for fighting was sufficient for the manual, they didn’t need xel’naga interference or queen of blades demigods.
That is why is think the story should be rebooted and re-focus on the first contact war as a morally ambiguous anthology sandbox setting. The fanfic bible “Starcraft: Enumerate” provides many helpful suggestions in that regard, even if I personally disagree with parts. https://www.sc2mapster.com/projects/enumerate-continuation
What hurts me the most is the incredible amount of wasted potential, all scrapped in order to recycle assets with Hybrid Dominator and Behemoth that barely look different from a Hybrid Destroyer/Reaver
At least we got the Hybrid Nemesis. I notice there are clear similarities between it and some of these concepts, particularly the weirder ones. But more variety would have been excellent, especially considering all the hard work that was put into the concepts.