Star Citizen is in active development, so things are going to change and shift around. That said, the most recent roadmap update has had a pretty surprising number of things in the “moved or removed” section.
A fair number of things are being shuffled to update 4.0, such as several weapons, the repair/refuel/restock kiosk, improvements to death animations, and the first version of a cover system and different weapon types in FPS combat. After that, the list is full of temporary removals in the face of shifting development priorities. Among these removals are dynamic missions that generate along QT routes and as a result of economic changes, the Cutlass Blue, expanded pilot and turret gunner roles, and the economy display terminal among other features. The Esperia Prowler has also been pushed back to release as part of update 3.9.
There have been some additions to the roadmap as well, such as ship system consequences for attempting ship combat at high speeds, the option for criminal players to surrender without being killed, improved interactions with the environment, and better ship AI pathfinding and collision avoidance. These features are also planned for alpha 3.9.
All of the details for what’s coming (and what’s not) are outlined in the forum post.