Theoretically, of course, the game could have an ending where the evil KaneDom in the final game betrays almost all of his allies, kills them and becomes the full master of the Karlsson empire, existing without a Board. But in this case, KaneDom simply won't be able to run the entire huge corporation alone. Even if Callista and Cole were to help him, they would all need some structure to replace the Board, as well as people with the right managerial competences.
Otherwise, Kane's absolute power would simply be meaningless. Besides, in the conditions of a dying planet, when time is running out and the question is whether all the remaining people on Earth will survive at all, the efficiency of managing the only structure capable of changing the course of history seems to me more important than simply ascending to the throne on a pile of skulls and announcing to everyone - I am in charge here! I am the King of the Mountain!
Okay, you're in charge, but the Earth is dying, and there's not a damn thing you can do about it without the help of Veronica, Astrid, Dominique, Cole and Callista. And it'll be a Pyrrhic victory. Is that the kind of victory we want for Kane? Personally, I don't.
I want KaneDom to seize power, get an obedient and intelligent wife, reliable submissive female assistants and obedient slaves, and rule happily ever after. And to achieve this result, the planet itself must survive, and for this both Kane and the above-mentioned characters will have to work hard...And if someone of those who are working on the revival of the planet, suddenly dies, there will be no chance for a conditionally happy ending.