In America anyway.
www.newscientist.com/article/mg20928005-600-4g-network-will-create-gps-dead-zones-across-the-us/?ignored=irrelevant
At the rate our Government could possibly roll out a 4G network here, maybe only Izaak should be concerned. 
PS - there'd be alot of p1ssed off speedsailors out there if they can't manage to solve issues though.
Good news. 4G gps dead spots is only going to be a US problem. It took a while to get a response but here it is ...
