FYI, what I heard back from Timbuk2:
I totally hear you! Quite a few people have been calling in looking for extra small laptop sleeves lately. Iâ€™ve forwarded your request on to our product development department. We donâ€™t have anything similar coming up soon, but hopefully weâ€™ll add an extra small sleeve to our repertoire soon. Customers have told us that our Eula tote is perfect for carrying the new super small laptops: http://www.timbuk2.com/tb2/products/bagbuilder/custom-eula
Thanks so much for the suggestion!