OnePlus 3 was a very marked improvement over OnePlus 2, "2016 Flagship killer". One Plus has been making quality devices at very affordable price range. OnePlus 3 packs Snapdragon 820 and 6GB of RAM. According to @evleaks, the company is now working on the faster version of OnePlus 3 and the device will be called OnePlus 3T. This new device will cost around $80 more than OP3.
The OnePlus 3T will have a improved processor. It will host newer Snapdragon 821 SoC. This is the same chipset powering the Pixel Smartphones. Other specs upgrade are yet to be confirmed, but OnePlus 3T will cost $80 more.
A3010, a OnePlus device model number was recently passed through Chinese regulators which probably could be new OnePlus 3T. The device could be announced in some weeks.