It's true that usually all 1Ls are on the same schedule, and that the schedule consists of civ pro, torts, and contracts in the fall.
I know that at least in fall 2013 the school had to tweak the fall 1L schedule because some of the professors who teach 1Ls in the fall were away, i.e., visiting at other law schools for a semester. If the school is adjusting the fall schedule again this year, I suspect it is for the same reason.
Before the school made the change in fall 2013, the administration took into account how other law schools have adjusted their 1L schedules and determined that students learned just as well on a different sequence. From what I heard afterwards, that turned out to be the case with the 2013 entering class and there weren't any problems.
I understand that it may be confusing at this point, but you needn't worry. I do not think that swapping one four-unit class for another will make the fall semester any more or less difficult. I agree that con law is a difficult class. I had a hard time with it during spring semester. But so is contracts. I found contracts difficult to learn in the fall. I would not be concerned about swapping them. I think you will find 1L to be academically challenging regardless of whether you take contracts then con law, or con law then contracts. I would be hesitant to place trust in anyone who uses this scheduling change as a reason to heighten anxiety or exploit uncertainty among incoming 1Ls.
As many people have remarked, schedules are not finalized until orientation. This makes it a hassle to buy books in advance. There's no ideal solution to this. The best I can say is that this is the only semester that you'll have to buy books last minute. For the remaining five semesters of law school, you'll have your schedule and booklist finalized in advance. Also, professors will be understanding during the first week of class. When I started 1L, some of my professors put PDFs of the reading assignments (for the first week) online. This made it easy to stay on top of the reading while I waited to get books.