A very quick fix would be to publish a radio altimeter check height on the chart.
Eg, when you go through 5D instead of referencing a largely useless baro indication you're shown what your rad-alt should be indicating. If it's wildly different, you know you've got a problem and go around.
Having said that Airbus already have a software solution. Nothing that GPWS manufacturers couldn't install either. I'm assuming that Boeing will continue to bury their heads in the sand when it comes to safety-related software improvements.