Alright, talk down to me here. Because, from my understanding, displacement mapping only requires a low poly base which is then expanded to about 3 bazillion polys, which are then remodeled, then they're put into the oven and shrinky-dinked into a managebable, but highly detailed low polygon count model.
Displacement mapping is basically a texture consisting of vectors that each vertex (corner of a polygon) is displaced by. It's what is used in ZBrush, a popular application for adding organic details to highpoly (cinematic quality) models. The resulting highpoly model can be used to calculate normalmaps (textures consisting of vectors that define the texel's normal vector for lighting calculations), aka Dot3 bumpmaps, which allow the realtime lighting to react properly to details that aren't there (not in the model, only on the texture). Any graphics card that's at least a GeForce 2 or has shader support (the GF2 didn't but supported dot3) will be able to display those. Games using them include Far Cry, Doom 3, Half-Life 2, Deus Ex: Invisible War, Chronicles of Riddick, Halo 2* and Thief 3. Unless Nintendo explicitely asked for shaders to be removed from the Hollywood chip, normalmaps will be possible on the Rev. The game never sees the displacement or highpoly models that were used to create the normalmaps (unless it's Doom 3 which has the normalmap generator built into the game binary).
*= Halo 2 used handpainted normalmaps, they weren'T generated from a highpoly source.
So thus the old franchises don't sell systems like the killer apps of a console should.
The old franchises would sell consoles like killer apps should if they were used to create killer apps. Remember, killer apps have to be both excellently executed and bring something new to the table. Super Mario Bros. created a genre. Final Fantasy VII introduced levels of cinematography never seen in games before. Mario 64 was the first 3d Jump and Run that was worth its salt. Halo introduced vehicles and coop to console FPS. GTA 3 reinvented the franchise to give it the best parts of an arcade racer and a 3d shooter, giving nearly unprecedented levels of freedom to players. Metroid Prime brings Metroid-style progression to the FPS genre (FPSes tend to be very linear otherwise, just as sidescrollers were before).