If the new MBA's are doing what the marketing slides claim they can with battery life on Mountain Lion, with then new features of App Nap and other aspects of Mavericks, it is conceivable that it might do better..
How the heck would we know...10.9 hasn't been releaed yet. Besides...if the new MBA gets 11-13 hours with 10.8...how many more hours do you want??
- Nick
Oh I'm happy with the 12 hours, I'm just intrigued that it could go even further
Let's not forget two things:
1. When most battery estimates are made you need to know the conditions under which those tests were made. Small changes in the test procedure (such as screen brightness) can affect the results.
2. Macericks should improve battery life but not all OS upgrades have done so for all users. I seems to remember having this discussion in the chat room shortly after eith Lion or Mountain Lion was released.