It's interesting that so many people who don't use the 1Dx are so willing to tell those of us who do use the 1Dx series what we need.
Everyone's use case is different. I use the 1Dx II almost exclusively for sports. For almost everything else, I find the R and 5D more suitable. As a sports shooter I definitely would like more resolution. I'm a one-man show. On the field or the court, I can only be in one place at a time. That means that if the action happens at the other end of the field or court, I have to crop. Even if it's a sport where you can choose a fixed position, it can require severe cropping. Who wants to get hit by a hammer or a discus? With indoor sports like wrestling, you pick your place at the edge of the mat and hope the action comes to you. If it doesn't, you need to crop. And, God forbid, you get two or three wrestlers competing on separate mats and you need to shoot them all. Even if the action is close, I usually have to crop because framing tight is a guaranteed way to miss the action. As Peter Read Miller says: Sports is messy.
Plus with Canon's current autofocus system, most sports shooters are using a single point or expanded single point, which also means that framing is compromised and you have to make it up by cropping later.
More than 99% of my images will live on the web. But there are some that will end up on a poster, billboard, or double-truck catalog spread. I have no idea which ones those will be, so I need all my images to have enough resolution for that flexibility if possible.
I really don't care about file size. Once the images are on the computer, it's going to take me the same amount of time to sort through 2,000 30 mpx images as it will 2,000 20 mpx images.
I don't have an assistant who receives the files and starts processing. I go back to the office after the game and do it myself. So, I could not care less about how long it takes to transmit a file over a wireless connection.
Sure, additional FPS are nice, but aside from a very few cases, the current rate of the 1DX II is fast enough (It won't consistently catch a batter at the moment the ball hits the bat, but I'd guess that 20 fps won't be enough either).
Now, if I had any evidence that 24 mp would give me cleaner files at 12,800 ISO than 30 mp at 6,400, I'd take the trade off. But that isn't likely to happen.
I'll take whatever Canon gives me, but please don't be telling me what I need.