I didn't see the keynote, just the blog updates, and two different liveblogs said MacBook. I just assumed that was a mistake. If Craig really didn't mention MacBook Pro, then it was probably still his just being unclear about it... unless somehow they've managed to make this work over USB-C.
The reason I say this is because the MacBook isn't due for a Thunderbolt capable update for a while, meaning 2019, unless somehow Intel was able to give Apple a semi-custom high volume run of 10 nm Cannon Lake Y series chips. I don't see Apple releasing a Thunderbolt 12" MacBook until Cannon Lake, since it would require another chipset that not only increases cost, but also uses more space, and uses more energy. My expectation was that Cannon Lake would add-in this functionality for free with no little extra space usage, and little extra power usage.