Nutty when/if developers start using more Pixel Shaders then the need for the TMUs which helps out in Multi-texturing will soften. The trend is going away from multi-textured games.
Why do you assume that heavier use of pixel shaders will mean less multi-texturing? You can multi-texture in pixel shaders you know.
As pixel shaders get _more_ powerful and faster, then we'll be able to do the graphics in less and less passes. Which means fewer shaders passes and more textures per pass.
The whole point of going from 4 simultaneous textures on GF4 to 16 simultaneous textures on GF-FX is to make heavy multi-texturing easier! I'd call 16 textures in 1 pass, pretty well multi-textured.
Multi-texturing and pixel shading are _not_ mutually exclusive.