We suggest a look at the presentation from Tire Technology Expo 2011 given by Dr Thomas Roscher at Audi AG. It provides a nice overview of what already has been achieved with TPMSs from an OEM perspective, and what benefits such systems (both direct and indirect) give.
The conclusion is that systems complying with FMVSS138 and ECE R-64 give enhanced safety, good driving dynamics and comfort, and ensure better fuel economy. Having that accomplished the recommendation is to focus on customer perception and nuisance free systems so that these kind of system get a good customer acceptance. Read the presentation here.