The NFL passed two rules that will impact offseason transactions. The league passed a rule that will allow compensatory picks to be traded starting in 2017. The league also passed a rule reducing the "tampering" period leading up to free agency from three days to two days.
There had been reports earlier this year that the comp pick trading would happen starting in 2016. The league decided against that, and if you the full resolution below, you can see they crossed out 2016 and changed it to 2017. That means the 49ers extra picks this offseason will not be tradeable.