"Although there have been reports that the 810 runs warmer than its predecessors, we assure you that we have taken all the necessary precautions and beyond to prevent this from occurring in the 2," OnePlus said. "We worked very closely with Qualcomm’s engineers to integrate an improved version of the chipset (v2.1) in the OnePlus 2, and fine-tuned both hardware and software. The 2 will be 'cooler than ever'."
That last line is borrowed from Qualcomm's marketing page for the Snapdragon 810. The page talks about the performance improvements of the Snapdragon 810 compared to the Snapdragon 801, and also posts temperature comparisons of the two chipsets when playing games or capturing 4K video. Have a look:
Source: Qualcomm via QTI Labs. Top is gaming use case, bottom is 4K video capture use case
"After rigorous testing, the 2 meets the industry standard for phone temperature, even with hours of use," OnePlus said.
Most other details have not yet been confirmed. That's intentional, as OnePlus plans to reveal bits about the 2's internal parts "piece by piece." That said, there are rumors the device will sport a 5.5-inch 1080p display, 3GB of RAM, 16MP rear camera, and a large battery measuring no less than 3,500 mAh.