OnePlus Pete just confirmed that there is no chance of Wireless charging on OnePlus 5T and only Dash Charging will be available. Here is a quote from the official Forum post:
Source: OnePlus Forums
As a product guy, it’s exciting to see technology advance from theory to implementation. We considered bringing this technology onboard, but we chose not to. Because it comes down to whether the solution actually brings a better experience. We'll consider adopting the wireless charging technology when the time is right. Until then, we'll stick to Dash Charge.