We configure our own kernel and I've been down the path of configuring x32 there, but afterwards, getting the user land to play nicely is another matter. Mind you, I was doing this on EL6, and so I needed to introduce a new glibc that co-existed harmoniously with the upstream one, and then bootstrap and build GCC with x32 support. Because we were evaluating software that already existed for x86_64, I patched Yum and RPM to accept x32 as an additional architecture. After all that, I finally ran evaluations on the software we planned to evaluate in x32, and found the performance gains were negligible (it was twemcache, which uses tons of pointers, fyi). I highly recommend doing your own evaluation first, before requesting such a large change to be applied community-wide. It may not be the panacea you seek.