IMO, they had something in development, and it failed to impress Nintendo. Rumour of the studio's imminent closure came up last year, and why not? The studio is a failed venture from a business standpoint.
It's likely Nintendo is sacrificing Metroid on them to avoid an EA-style PR disaster when closing the studio. Fans are far more likely to support the studio shut down if they fail with a much anticipated game.
I describe myself as a little dose of toxic masculinity.