As I understand it, the basic problem that various authorities have against use of GPS for sole/primary navigation is the dependence upon a single system.
If however you can have a GPS and a Galileo box in your cockpit - with separate hardware, separate satellite systems, but the same free-flight functionality - we can all bin VOR, ADF, LORAN and all the rest of the low-accuracy high workload navaids and simply cross-check between two near-identical satnav displays. Equally an autopilot need only compare two identical nav inputs and scream help if they aren't within a few hundred metres of each other.
It may be expensive, but unless you support the US military's GPS monopoly, love ADF mental arithmetic, or earn your living selling or maintaining VOR equipment it's hard to see it as a bad thing.
But, going back to weasil's original point, if Galileo was compatible with GPS you wouldn't have this advantage of redundancy.
G