Yes, the MCU did it with The Mandarin and Teenage Mutant Ninja Turtles sort of did it with Shredder (when test audiences were outraged that he wasn't authentically Asian) but the old villain switcheroo is still unexpected enough to work. While everyone is happily floating along on the assumption that Oberhauser is Blofeld, despite Christoph Waltz's adamant defiance, the film might be about to throw the curve-ball that Scott's Denbigh is actually the real big bad. That would explain why M is seen fighting with him in the trailer, and his evil forehead would suit the revelation that he's the real bad guy. There's already been some theorising that Scott actually speaks one of Oberhauser's assumed lines in the second trailer - specifically "you came across me so many times, yet you never saw me" - which would be pretty damning evidence that he is in fact the real puppeteer behind Spectre.
