If only i had the cash...
But I see two options for those who do.
For the same price, either 1DX, or a 5D3 + 1D4 kit.
The 1DX is a 'does-it-all' camera, the AF is going to be better than the 1D4 for sports, the IQ will be better, the low-light will be better, there's 2 (or 4) more FPS. 1 of them in your bag and you don't need much else.
But for other people, especially birders, the 1D4 is more attractive, f/8 focussing and more pixels-on-target (i will be *very* interested to see the results of 1DX cropped to same FOV as 1D4 and printed same size, and i'm sure i'm not the only one), and the 5D3 can be the landscape/wedding/low-light camera. Depending on the price of the 1D4 and if you wait long enough for the 5D3 price to settle, it won't be much more expensive than a single 1DX, with the plus that you get a backup camera if one carks it on a shoot (either is not as good as the other for specific use cases, but 'good enough' and better than packing up and going home).
I don't see many 1D4s go on ebay, but the ones that do are still in the $3k-4k mark. I'm tipping them to be averaging under $3k if the 1DX gets f/8 in a firmware update before release, maybe $2.5-3.5k by the end of this year anyway. If they end up the same street-price as the 5D3, i'm going to have a very difficult decision on my hands (i'm not going to afford either without selling the 7D, that will be hard enough as it is, i love that thing)...