All of the vulnerabilities have reportedly been fixed in Yosemite 10.10.2, the next build of the OSX, currently in beta and due for release soon. Apple had to change the code to not only prevent the Mac s boot ROM from being replaced, but also to prevent it from being rolled back to a state where the attack would be possible again, according to Apple news site. At least until the patch is fully deployed, MacBooks will remain vulnerable as they re subject to downgrade attacks.
Source: https://threatpost.com/thunderstrike-patch-slated-for-new-os-x-build/110649/