Well stewer said in another thread that the hardware shading of poser's viewport is done with Cg, so i'd settle for just having the ability to use custom Cg shaders. That alone would mean you could create shaders to do normal mapping, basic IBL, basic SSS, some raytracing and nice looking shadows, all in the viewports. Also stuff like realtime AO, bloom, depth of field and tone mapping like in mudbox. It would easily become a very nice alternative to FF for animations and quick renders.

As for not being able to exclude lights, yeh it sucks as it means it's real hard to do any sort of complex lighting in poser. Not only is there no GI, but you can't easily fake it either with hand placed lights.