It's been known for a while that there was to be some kind of expansion/sequel in which the Empire does strike back against the Thalmor.
There is a removed line from the game — in early builds of Skyrim, if you won the Civil War for the Empire, the woman who is like second in charge (Rikke?) makes a remark about how the Thalmor are next. It was thought that this was removed as plans changed.
However, in Fallout 3, the Institute/Railroad quest originally referred to the robots as Androids. That game came out in 2008, the year Google released the first Android phones commercially, and the iPhone came out the year before, so we (in the Fallout fandom) were speculating that the Institute would be like Apple led by a guy like Steve Jobs who was trying to rid the world of Android (like he said about waging thermonuclear war on Android as he considered it a stolen product). When plans for Fallout 4 began to take shape, Fallout 3 was updated to call them Synths instead. That was the confirmation that the Institute, the Railroad, and the ~~Androids~~ Synths would play a pivotal role in Fallout 4's story. Once Bethesda was caught scouting out Boston, a lot of us guessed that the Institute would be MIT (Massachusetts Institute of Technology) and a lot of the rest kind of fell into place. (There was still a lot we didn't know, such as young Arthur Maxson from the Brotherhood of Steel, just a scribe in Fallout 3, turning into a literal fascist and taking the Brotherhood to Boston. That was a wild ride.)
There was an alternate theory that Bethesda changed Androids to Synths so as not to bother Google over the Android name. IIRC Google never asked them to change it, but some said they did it just so as not to be a bother. I never bought this story, but before anyone says "well there were Android phones so maybe that's why," yes, that theory was floated and some people believed it. I can't speak to numbers or percentages, but I didn't buy it. Plus, the term "android" is older than Google. I'd credit Asimov for it, but I'm not sure I'd be correct.