I lean towards Wii U, although PS4 and PC will probably come close because of their larger user bases.
RE: The argument that Wii U audience =/= N64 audience, I disagree. Outside of the Wii, the audience for Nintendo home consoles has been quite consistent since the N64 days or even earlier; platformers, puzzle/party games and action/adventure titles are all generally good sellers. Yooka Laylee belongs to the genre that has been Nintendo's bread and butter longer than any other, and a lot of Wii U owners are long-time Nintendo fans who reminisce about Rare's good old days. Rare doesn't have that same history with Microsoft, and they don't have any of that history with Sony or on PC. The old guys from Rare reuniting for a new game? Arguably a bigger deal for Nintendo fans than for anyone else.
Also, it's worth mentioning that most of the guys at Playtonic are Nintendo fans themselves.
RE: The argument that owners of different consoles will buy the PS4 version because it'll be more technically powerful - from what I've seen only people in the echo chambers of the Internet really care about that. And Playtonic are probably not lazy devs; if they make good use of the Gamepad, the Wii U version could well end up with its own set of advantages.
I would tentatively guess sales to split around 35% Wii U, around 30% PC, around 20-25% PS4, and around 10-15% XO.