The sequel will follow the ending where you kill both Demichev and Barisov
...And Renko will be the new Big Bad. The third ending sequence implies that Renko ends up becoming a merciless dictator like Demichev. It's very likely that Renko will grow unsatisfied with merely ruling the old USA, and launch a Take Over the World campaign, and it'll be the job of the new protagonist to stop him.Singularity is an alternate-continuity BioShock game, with time-manipulation powers instead of Bio-Augmentation or bottled Functional Magic
BioShock Infinite states "There's always a lighthouse, a city, and a man". The Demichev Reactor, the Katorga-12 facility, and Renko could be seen as fulfilling that criteria. The TMD takes the role of plasmids/vigours. That's the reason it's so similar.There is no Translation Convention with the signs in English in Katorga
With an incredible scientific discovery like E99, it's hard to not think that the Soviet governement would have pursued the help of scientists from outside the USSR, even leading some to defect their own countries just to research it. This, however, made necessaary to use signs of another language to help them around, and English was the most obvious choice.The "Don't trust Barisov" note predicts his ending
One of Renko's past iterations figured out that Barisov would simply conquer the world himself if his plan succeeded. He tried to warn future iterations because of this.- In addition, the "Don't trust ME" message relates to his efforts to stop himself since he doesn't know whether the alternatives are any better.
Barisov planned his ending
Barisov is a dedicated Communist. He may oppose Demichev's methods and rulership, but the idea of the USSR and Communism dominating the world wouldn't sound too bad to him on principle. He may be working with you, but that doesn't mean he automatically wants the Americans to come out on top. With Demichev's threat gone, but the TMD developed, he could Take Over the World himself and run things his way instead.Alternatively, Borisov has Ripple-Effect-Proof Memory just like Renko
Borisov seems well aware that his and Renko's plan to blow up the reactor failed. If he weren't, he would have thought a new reactor being built was how things always went. He simply took advantage of this knowledge and/or the conveniently intact TMD to complete his research without the catastrophe at Katorga-12.