Apparently, quite a lot of people have been asking Mr. Mackenzie about the updates after he said the One would be going straight to 4.3. And, lucky for us, it looks like he has gotten the okay to actually tell us what's happening. According to Mackenzie, HTC is working hard on the Android 4.3 updates, which need certification right now. The plan is to be able to release the update to "all US, Canada SKUs" by the end of September.
Best of all, this isn't just for the HTC One, but this news also covers the HTC DROID DNA. So, it looks like HTC One owners should be getting the 4.3 update in just over one month. DROID DNA owners, well... we'll believe it when we see it, given Verizon's history of delaying testing software updates.