Here's the thing, it's almost certain that it can't get any better, at least financially, and that's the problem. SW8 almost certainly won't make as much as 7 did. Marvel, while consistently good to great, has almost certainly peaked financially. The parks have record profits and still need to cut to the bone. There's no property like Star Wars/Marvel that's available for purchase
I'm not saying Disney is in any trouble of going out of business or anything crazy like that, but they've certainly reached a point where it's hard to see them do anything but stumble in the eyes of Wall Street.