Approval in aviation is hard, no argument there. Everybody making a GPS is aware of jamming issues and looking at what their options are. I doubt there is any option that isn't expensive and years out from airplanes. However they are likely to start rolling things out in the next few years just because they need to do something.

Don't forget there is a lot more than aviation. Hikers will want jamming protection if it isn't too expensive (depending on what protection we are talking about it come be cheap or expensive)