Why it matters: One of Nintendo's most anticipated Switch exclusives is going back to the drawing board after the current studio was unable to meet Nintendo's standards for quality. The hiccup will delay the game's launch by what could be a couple of years, pushing the title much later into the Switch's lifespan than Nintendo initially hoped for.
Metroid Prime 4 was first announced at E3 2017. Rumors surfaced in early 2018 that Bandai Namco was working on the title. It was originally thought that Retro Studios, the developer behind the first three Metroid Prime games, would get the nod but Nintendo confirmed that wasn't the case shortly after E3.
On Friday, Nintendo executive Shinya Takahashi revealed that development of Metroid Prime 4 has not reached the standards that Nintendo seeks in a Metroid Prime entry. Specifically, Takahashi said the current development status of the game is very challenged and they have decided to "reexamine the development structure itself and change it."
In other words, development of the project is being halted. Current progress will be scrapped and development will start over from the beginning under the guidance of Retro Studios.
Naturally, a change of this magnitude will delay the game's launch. It's probably safe to assume that the game won't arrive for several more years - late into the Switch's lifecycle. That's far from ideal but likely the right decision if the current product wasn't up to Nintendo's standards.