According to all official info - unfortunately this is the last DLC. They will show something new during the E3, but it won't be Cyberpunk 2077. They want to release another AAA title this year, but it's not Cyberpunk or Witcher.
Also, there won't be any more Witcher games, as they moved their focus onto the Cyberpunk 2077, +100 devs are working on it now. And they said Cyberpunk 2077 will be much bigger than Witcher 3. Maybe there will be Witcher 4 but they focus on the Cybeprunk 2077 until it's released.
- - - Updated - - -
According to the lore - the true ending is her becoming a Witcher, as i'ts her dream and goal. Other endings are "non-lore".