Thanks oktas8 and 27/09. Makes much more sense now.
I think I get it.. For the GA guys and gals we are going to have to wait for multi frequency or dual channel gps which allows for multiple gps constellations to provide data to a single gps unit. This would mean a hardware change but essentially you would be receiving two gps feeds. Therefore the unit could do its own error correction.
From all my reading it doesn't seem to be something that will be deployed in the near future. 2020 onwards I think.