After development of Metroid Prime 4 was restarted and handed over to Retro Studios, little was heard about the title. But on the 18th, the company announced via Twitter that it was looking for an Art Director for the game. 

RetroJob

Retro Studios is looking for an Art Director who can lead the collaborative development of Metroid Prime 4's art direction. The position's duties include:
  • Establishing an artistic vision and providing feedback and direction to enhance that vision
  • Working with our development team to ensure that artistic priorities are effectively defined and that processes meet artistic quality and scheduling goals.
  • Collaborating with the art team and our parent company to bring effectiveness and consistency to communication and art direction
Apply here: https://careers.nintendo.com/retro-studios/

The company had already been looking for people to work on the title since April, but it appears that no one was yet filling the role of Art Director, a considerably important position.

MetroPri3

Metroid Prime 3, developed by Retro Studios

The announcement that development was restarting was made at the beginning of the year, on the grounds that the game was not meeting internal expectations. The project was therefore handed over to Retro Studios, the company previously responsible for the Metroid Prime series.

The search for an Art Director indicates that development of Metroid Prime 4 is still in its early stages, so the game is not expected to come out in 2020.