The balance of powers between the three branches of the federal government does not shift in any predictable or systematic way from year to year. Over the years, the executive branch has become more powerful, but this does not necessarily happen on a year-to-year basis. In other words, we cannot know that the executive branch will have more power next year than it had this year. Instead, power shifts somewhat randomly, depending on political circumstances.
Over time, the executive branch has gotten stronger. This has generally happened because of wars and other crises. When the country faces a crisis, Americans generally want the President to be strong so as to lead them out of the crisis. When this happens, the executive branch gets powers that it rarely relinquishes after the crisis is over. In addition, the increasing importance of the media has helped presidents gain more power over Congress through the years. This is because the President is the one face of the country and can get plenty of media attention very easily. Members of Congress have a much harder time, thus making it much easier for the president to lead the country.
From year to year, though, the balance of power between the branches does not necessarily change. It changes randomly, based on circumstances. If there is a major crisis (like the 9/11 attacks) it shifts to the executive as Americans want strong leadership. If the economy gets worse, the president’s approval ratings can go down and Congress can gain some power. If the president and Congress are of different parties (as things are now), a stalemate occurs, with the two branches’ powers canceling one another out. Power can shift based on whether the President is a particularly effective or ineffective politician. Power can shift if a Congressional leader arises who is a very good politician. All of these are relatively random things, so we cannot predict which branch will have more power on a year-to-year basis.