I think Etherboot and FILO are dead almost, because we intend to put tiny kernel and kexec on the flash.
Tiny kernel, like 32kb?
Not with linux. He's talking about the tiny- patches that have been (mostly) integrated in to the mainline linux kernel. Using these patches linux gets much smaller. Although its still pretty large.
Or tiny kernel, like replace bios completely?
For OLPC we have linuxbios+kernel+initrd all in 896KiB. (We lose 128KiB of our 1MiB due to some other firmware) It has USB and can boot jffs2 or ext3 filesystems and small graphical boot selector with fancy icons. It also has a busybox ash shell for when the booting fails.
With the new LZMA compression we plan to get TCP/IP stuck in there as well.
So with 1MiB you can now have all the functionality of etherboot+filo.
Can you get there for smaller parts? Don't know yet. If you drop jffs2 all the shell stuff then 512KiB has a really good chance. 256KiB will be a bit more of a challenge. You may have to move to an "in kernel" loader.