The box office drop doesn't surprise me all that much since X-Men was pretty much going to crush anything that came before it. I don't even see Malificent knocking down X-Men next week. Why is everyone so fidgety about this?

For all intents and purposes the movie is a success, and people expecting it too go on to make 700 million were way ahead of themselves. 500 million is a safer number and it'll easily make that number.
The movies are a changing market and the next big market is China. Expecting the movie to do well in China is not grasping for straws, or or false hopes. It's common sense if you're in the business of well.... ANYTHING. Newer people are entering the middle class every year, giving them luxuries like TV, Movies, music and video games that were not there a few years ago. It only makes sense for movie companies to release movies in China, a coveted market EVERY studio is trying to get their share of.