The hybrid system would likely be what WN does. You can earn status either via spend based points, or via a number of "flights". Note that WN does not count segments. Each one-way trip, regardless of number of segments, counts as one flight. No, I wouldn't be surprised if DL (and the other legacies) move to something similar to what WN does now. Would I be disappointed? Sure. But ultimately I realize that WN's system probably makes the most sense. As you noted, it's also very much like the hotel programs.