It looks like we may have been on the right track, as it didn't take too long for HTC to almost confirm the Desire 820's 64 bit-ness in another teaser image. Not just that, but Qualcomm itself joined the party by acknowledging the device as the first smartphone to use its octa-core Snapdragon 615 SoC.
The Snapdragon 615 processor itself is a upper mid-range CPU that utilizes four Cortex-A53 cores clocked at 1.8GHz and four Cortex-A53 cores clocked at 1GHz. Its visual crunching partner of choice is the Adreno 405 graphics unit. Eventually, the Snapdragon 615 will be succeeded by the Snapdragon 810, which will make use of Qualcomm's powerful Adreno 430 GPU and is designed for 2015's flagship Android devices. A glorious time to be alive, isn't it?
The HTC Desire 820 should be formally announced at September's IFA expo in Berlin, two weeks from now, and you can be sure that we'll be there to meet it in person!
HTC Desire 820 smartphones
via G For Games (thanks for the tip!)