War Horse was only nominated because the Academy now allows up to 10 films to get the Best Picture nomination - as a specific response to the negative reaction to the nominees in 2008. It will not win, since the real race there is essentially down to The Artist and The Descendants. The favorite seems to be The Artist, which again seems likely to sweep three of the most important categories.
Keep in mind that the Academy seldom goes with the big budget movie these days. They are more likely to go with the smaller budget, more independently minded movie. Look at the last few winners: The King's Speech, The Hurt Locker, Slumdog Millionaire, No Country for Old Men. The Hurt Locker in particular is instructive: it was a modestly budgeted movie about a munitions-clearing team in Iraq. It was filmed under difficult conditions in the Middle East, and it overcame all odds to get made and get Kathryn Bigelow a DGA award and an Oscar. This year, there is definitely popular sentiment for Martin Scorcese, as there was for James Cameron with Avatar. But James Cameron and Avatar did not win the major Oscars. Those went to The Hurt Locker.
Martin Scorcese also just won a DGA Award and an Emmy in the past year for his direction of the pilot episdoe of Boardwalk Empire. He won Best Director for The Departed five years ago, most likely in recognition for his long and distinguished career to date, as is normally the case with the Oscars. Many people finally win an Oscar for something after having been nominated multiple times, and the eventual win is almost a cumulative nod. Given that Scorcese won a DGA Award so recently, it's not likely that he'll immediately get it again. The more likely winner will be Hazanavicius for The Artist, for the pure audacity of making a silent movie in 2011, and for making it in such a charming fashion. Of all the nominees for the major categories, only The Artist has that distinction - it's the kind of idea the Academy tends to reward. And the movie is a valentine to the golden age of Hollywood, which never hurts either.
I'd look for Hugo to pick up a few more technical awards as a nod to the great work done on the movie. And I'd look for The Artist to take the Picture/Director/Screenplay trio. The acting categories will be a different story, but they usually are.
Steven Spielberg will be nominated again within the next few years. He's usually nominated for his more serious films, like the two for which he finally won Oscars in the 1990s. His last nomination was for Munich, which was the serious film out of the two he did in 2005. He wasn't nominated for the 2008 Indiana Jones movie, and I doubt anyone expected him to be nominated for Tintin. But you may see a nomination for Lincoln, if that comes out as well as it looks. I doubt he's much concerned about getting another Best Director nod this year. He'll make plenty more films and get plenty more nominations and awards down the road.