The problem is political inertia. It takes the authorities ages to respond to technical advances. In an ideal world a decree would be issued by all aviation regulators:
On and after 01 January 2018 all altimetry and navigation will be GPS based.
No more TAs and magnetic navigation! Pressure altimeters (automatically set to local sea level air pressure via data link) and compasses (with local variation data available on EFIS displays) only for back-up.