The Reddit AMA by the OnePlus team has been a fruitful one it revealed that the 3/3T will get Android O by the end of the year and also that the OnePlus 5 is getting EIS for the 4K video recording mode.
EIS Electronic Image Stabilization was always in the plans, but was not completed in time. The team chose to focus on 1080p stabilization as well as stabilization for the selfie camera. 4K EIS is coming, though OnePlus did not commit to a time frame.
Also, the team is aware of Wi-Fi connection issues, which will be fixed in the upcoming build. The issues with Vodafone NL are being worked on as well (to be resolved soon).