They should have been shuttered well before Prime 4, but given their industry worst track record of selling Nintendo on flashy prototypes they habitually fail to flesh out into full games, it will be nothing short of a miracle if a Prime 4 is ever shown at all, nevermind releases. Luckily Nintendo has plenty of fools buying dozens of broken $80 controllers and $100 price hikes on half decade old hardware to fund Twitter BBQ memes for another 10 years. And yes BotW2 is an embarrassment in its own right, 5+ years for a recycled asset expansion pack.
What? those 2 games are among the best 2D platformers on the market, Returns sold close to 10 million, and Tropical Freeze around 5. They were important and successful games for both Retro and Nintendo.