Boozer will end up dying.
It seems like something they would let you do, or to even just ignore giving him meds for his arm completely- Jossed. Boozer survives the whole expreince, though there's at least two fake out deaths. And there's no option to not give him meds, as it's required and they have seemingly stripped the choices seen in earlier bulids.
Sarah is going to appear in-game as a Freaker
Deacon's journey will take him to the last place he saw her and she'll be there just infected.- Jossed. Sarah is alive, lives through the rest of the game and actually helping research the infection when you find her, though at first you are lead to believe she died somewhere else.
The sequel will become a "Omega Man/I Am Legend" Tale
Going off the ending section where you find out Nero is run by intelligent freakers. Leads this troper to believe that in the sequel Deacon and the other human survivors is going to go into the fact that humanity is now viewed as "monsters" to this new developing freaker society as Freakers seemingly outnumber humans 100 to 1 in terms of sheer countable population and are shown to be evolving rapidly. The Freaker Virus is mutated Syphon Filter Virus
One of the collectables is Gabe Logans Air Taser, implies the existence of the IPCA in Days Gone, which the main games were about trying to stop a highly deadly and mutable virus being released, in Days Gone, perhaps someone succeeded in gaining some and releasing it.- Jossed. You actually find a collectible in the Cloverdale Labs that mentions Cloverdale was working on the virus Syphon Filter before the apocalypse. The Freaker virus was very specifically a different project.
Days Gone takes place in an Alternate Continuity where IPCA failed to solve "Omega Strain". IPCA was officially dismissed by U.S. government from the whole Syphon Filter affair for this failure and was tasked with new assignments completely unrelated with virus outbreak.
If IPCA is still working on dealing with virus outbreaks, then the main characters should be Gabriel Logan and Lian Xing, and United States would have no need to form a new organization.