I noticed in a recent post to the u-boot list that Hans said that booting from sata now works with the latest upstream uboot and 3.19 kernel. So I asked him to clearify and he said that you still need the SD card, but just for the uboot. ALL partitions can go on your sata drive. I further suspect that even I can figure out how to get the uboot to NAND, so that no SD card is needed. This might even be able to be implemented in an install script that a lot of users can deal with. And that is where we get past crawling to walking. When you run a script, only providing the location of the .xz file and your board, and the install goes. Well at least to the part where you have a bootable drive to install into your system.