Rare has always been and continues be a company with an incredibly diverse portfolio. You can go all the way back their humble beginnings to the present day and see how they've always worked on games that cover a variety of different genres. Platformers (2D & 3D), racers, fighting, shooter (FPS & TPS) puzzle, simulation, action/adventure, sports, and now an MMO. And their output on the Nintendo 64 was miraculous and nearly rivaled that of Nintendo themselves, with every game they released selling millions of copies with the exception of Conker and maybe Mickey's Speedway USA. Say what you will about DK64, but it still sold over 5 million units.
Even before the buy out, Rare had Perfect Dark Zero, Kameo, Donkey Kong Racing, Starfox Adventures, Grabbed by the Ghoulies, Diddy Kong Pilot, DK Coconut Crackers and Banjo-Kazooie: Grunty's Revenge in development. Maybe even more than that! Heck, DKR, Kameo and Starfox were even on the back of the GameCube box!
And there was no max exodus of employees. It was a handful of people that went with David Doak to form Free Radical and Martin Hollis who went on to assist Nintendo with hardware development of the GameCube.