Speculation isn't really a spoiler, so I don't see why the tags are needed. I think we're becoming a bit oversensitive to spoilers, I mean anything can happen; there are countless ways Nolan could end this franchise.
Personally I don't see a continuation of the trilogy into a new series of movies as that is not what Nolan would want. Warner's and DC obviously would want a continuation, but I believe Nolan has full control over this franchise, and the only way he can leave his definitive mark on the franchise is with an ending.
Also knowing that Nolan is producing the Superman franchise, does anyone think Supes will be mentioned in this movie, or maybe they'll release the first trailer after the credits? I could see that happening since Nolan is in control of both franchises.