I think it already does. It depends entirely on what you mean by "Core" gamers. Do you mean someone who plays a lot of games and has been gaming for a LONG ass time, like myself? Or do you mean someone who is basically one of those "HARDCORE" gamers, who only considers "Realistic and mature" games with plenty of shooting and/or violence, blood, erotic material, etc., to be "real games"? The second category are nothing but immature poser fanboys who need to grow up, and seek mental help.
The first category? They, like me, buy what they want, and play games that they like, because they're good/fun. So yes. I think the Wii U can/does absolutely appeal to "core" gamers. But by asking that, do you mean will it EVER appeal to the shooter-monkeys and "brocore" gaming crowd? No, if nothing else because they wouldn't be caught dead owning a Nintendo system. Their friends might make fun of them.