I'd hesitate to call them a new Rare, because they approach things very differently. While Retro has been mostly focused on revitalizing and putting a new spin on established Nintendo IPs, Rare was more about making entirely new franchises. Banjo Kazooie, Killer Instinct, Conker's Bad Fur Day, Battletoads, Perfect Dark, etc. Even the games that did involve a pre-established franchise, like DKC or Star Fox Adventures, played nothing like previous entries in the series, and in the case of DKC, basically created the Donkey Kong universe that exists currently. And Star Fox Adventures wasn't even going to involve Star Fox at all until Nintendo intervened.
Perhaps put it simply, Retro has been what Nintendo has turned to to bring a forgotten franchise back to prominence, while Rare was more of a creative bucket for entirely new ideas.
