1) Haswell will not rival the GTX680. Maybe the GT430 or so. It's a major step up for Intel, sure, but it's not going to make the discrete guys sweat. Broadwell *may* break into at least the low end of enthusiast-class GPUs, but that's a year+ off yet. Also, Intel's drivers historically kind of suck.
2) The reason to do hw rasterization in MAME is the now-reasonable installed base of ATI and Nvidia cards that are capable (ie, DX10+ compliant).
3) MAME will never add effects to games that they didn't have originally. Ridge Racer will have no filtering and certainly no ansiotropic. No artifical resolution boosts either - we'll draw to an off-screen surface the size of the original game and then HLSL that up to your monitor size, just like we do now.