Great job guys!
Context : I like Gentoo enough that I'm working on a publicly available pkgbuild set of every current stable amd64 ebuild (using the default flag combinations ) because I'm sick of hearing people say they switched to Arch because they "hate building from source" and they "never customised the flags anyway so why bother".
I think the biggest problem right now is the constant shunning of variations like Exherbo. So we have ChromeOS, CoreOS, Exherbo, Funtoo, Gentoo, Sabayon, and others I'm to tired to list, all using ebuilds ... But no real effort among any of them to work together at all. I honestly think we need to rally around the ebuild format and get some cohesion going. /rant
It's unlikely changes like these would ever be introduced in Gentoo, for multiple technical and more importantly social reasons. Gentoo has a big problem with accepting sound technical ideas because they come from politically incorrect people.
FIrst of all it could make things a lot easier for many people and/or companies doing embedded development and relying on cross compiling.
And secondly Exherbo is sending a significant amount of patches upstream and follow up on them to make sure they're accepted by the upstream projects. This should benefit all of us and not just the minority using Exherbo Linux.
So all in all I see plenty of reason to be excited about this development even if you're not an Exherbo user.