When Galileo/EGNOS (together with GPS, even GLONAS) are fully established as truly civilian controlled infrastructures
Because of course there's no way for the US military to deny Galileo in any theater they so choose...right..
....I mean they had no say or input into the design process..Its pure "Made in Europe"...
...I think you know where I'm going with this.....
Interestingly enough if some mad group of god knows who, decided to wage some GPS enabled mayhem on US soil it would pose quite the dilemma with much of the entire countries communications infrastructure now utterly dependent on C/A code derived timing.
For the paranoid wishing for the ultimate diversity there are very practical ways to obtain very good GPS compatible positioning solutions from other rather more mundane and ubiquitous signals also. For example TV signals
Rosum Corporation. Rosum - Reliable Location. Inside and Out. (Fair disclosure: I worked on this one). Would I want to build one to the necessary aerospace standards...hmm, the jury's out on that one.