There are two approaches to dealing with the light fall-off from oblique rays hitting an FF sensor, both of which are realistic possibilities:
1. Via camera firmware or digital darkroom like Photoshop (which is easily done already.)
2. New sensor with improved sensitivity towards oblique rays.
I expect these breakthroughs to be available in a few years' time. Meanwhile we already have the Fuji F10/11 with dramatically low noise at high ISOs - a result of better noise-reduction algorithm, an improved sensor (is the SuperCCD made by Fuji themselves?), or a combination of both.