If you'd have read developer reviews from Retro Studios in the run-up to the original Metroid Prime, I imagine people would have said a similar thing - Retro was in absolute chaos until Nintendo took closer control.
It doesn't take a lot, at this point, to guess that at least one Retro project in the last four years or so has entered development hell and that would understandably put a lot of pressure on the staff. When the Star Fox Grand Prix rumours broke, Kotaku were reporting that another Retro title was in development hell and likely on track to be cancelled, which might be behind these negative reviews. As for Nintendo shuttering the entire studio, if the Star Fox game is real, I suspect that Nintendo will try to get that out the door first. Like I said, back in Retro's early days, the studio was absolutely chaotic - and Nintendo were throwing money at them, burning cash. Despite the losses and the lack of results, Nintendo still hunkered down, took control of the situation and kept faith with the staff they kept on at Retro, and the Prime games were the result.
Not saying we should expect history to repeat itself, mind, but I don't think this should be taken as the studio's death knell, either.
EDIT: Should also be pointed out that, while Retro haven't put out a new game, they did handle the Switch port of Tropical Freeze - so they clearly still are active to some degree.
