I just logged in my eUpgrade account and noticed this:
So, O fares have the same eUpgrade requirements as Latitude now. E, N become discounted (I assume) PE fares and have the same requirements as Flex.
I was able to confirm all my upgrades on my trip to HKG next week since I booked O class when that was the only one available.
Curious about the accrual rules (and price!) for these...