When you say Hardcore Nintendo fan then you mean either the ones from the NES/SNES days. Maybe the fan who stayed around and bought a N64, and Gamecube. These fans are not going to care as long as they get Mario, Zelda, and other Nintendo games. Now your Pretendo fans who have Nintendo consoles, but want 360, and PS3. Then maybe if Project Cafe can make them happy. If the system has the power that Western developers want, and provide something to get the Japanese gamers back to consoles. Then Project Cafe could become what the PS2 was or what they Wii could have been. A console that everyone will play with Class A first party titles, and equal 3rd party games. Nintendo can use their games to build the userbase, and the 3rd parties games to tie hungry gamers over.
Regardless of it being HD or not real Nintendo gamers are not going to care. As long as Nintendo keep doing what they been doing. Now your Pretendos they are the wild card, but If I was Nintendo I wouldn't care about them anyway. Whatever they do find a way to bring the new casual, and expanded gamers with you to the new system.
