i think this article describe it best: (not necessary a fan of Bruce)
http://www.bruceongames.com/2008/08/12/hardcore-gaming-is-dead/
"By hardcore I mean that they were in narrow genres, were progressively more complex, were difficult for the neophyte to get into and appealed to a large but still limited demographic"
"What will happen is that the existing hardcore genres will continue. But they will become less obtuse and more user friendly."
"So hardcore as we know it will no longer exist. Instead there will be shades of grey between the two extremes of what are just now known as hardcore and casual."
PS There are still a few very hardcore games on the PC so they do still exist. One of the advantage of the PC is users mods which turns some games more hardcore.
