I'm sure that, if you spend enough on the receivers, you could realize some gains, but how much will it cost? Maybe you can build a consumer-grade GPS receiver that would be less susceptible to interference from LightSquared's network for some amount over what they cost now, but, at some point, it isn't economically viable to do so.
But, even if there are gains to be realized, that also applies to LightSquared. After all, if their receivers can be made more sensitive, then they could use lower-powered transmitters, which would reduce their effect on GPS. So, unless their receivers are the model of efficiency, then they're having to transmit with more power than necessary, which is creating unnecessary interference with GPS.
But, IMHO, in LightSquared's case, it comes down to a company wanting to do things on the cheap. If they wanted to build this network, did they bid in the AWS auctions a few years ago? What about the 700 MHz auctions? As I recall, the D block didn't even sell. It would have made more sense to go for some of these frequencies instead of trying to use the spectrum they have now. And, really, they aren't out of the game anyway. Why not use low earth orbit satellites? That should be an option still on the table for them.
reply to FBGuy
Even the best designed band-pass filter will does not produce sharp contrasts across the close frequencies. You have to balance the loss of the original signal with the sharpness of the curves of allowed outside frequency. Making the curves on the outer bands costs of the recieved freqs, not money.
I got an idea, take some Electrical Engineering classes and design that sharp band-pass filter, and you'll rake in the dough. The band passes are idealised as a trough, but in reality, the filtering effect to near freqs are not straight up and down, but actually go at an angle.