I think we need to rethink this attitude of games selling systems, although it may be that way for many of us, in general a hardcore game is not going to encourage a more widespread audience to purchase a console.
What we are seeing with the DS is the system being able to sell games, quite amazing sales numbers have been posted recently. Zelda, Yoshi's Island, Ouendan 2, Phoenix Wright, Kirby and New Super Mario Brothers have all gone against trends of decline in a franchise, and these are all hardcore games. However I feel that hardware has been pushed much more strongly by the likes of Brain Training, Pokemon, Animal Crossing and Nintendogs, less hardcore games (softcore?).
On the other hand PS3 sales have been consistently poor, big hardcore franchises like Gundam and Virtua Fighter have been unable to ignite them. What PS3 really needs is a softcore game that uses the features of the PS3 to a great capability. Perhaps something like Little Big Planet or a PSP/PS3 crossover online "experience" could help.
Anyway that's my take on things, let me know what you think.