I'm not sure, to be honest. Outside of Nintendo, the 3D platformer has more or less faded into obscurity, but if marketed correctly maybe one could make a decent splash.
There seems to be a lot of grassroots support for A Hat in Time, which is a good sign. And it was only eight years ago that Daxter broke 4 million in sales.
Now in Rare's case, the problem isn't only with the audience, or lack thereof. It's with the developer, which hasn't proven it can produce a great 3D platformer, and the publisher, which hasn't proven it even wants such a game. Would I love a new Banjo or Conker game? Yes. But I don't trust Rare to make one and I don't expect Microsoft to commission one.
I would love to be proven wrong though.