London Economics mentioned Satelles STL as a possible solution in a recently released  report entitled “The Economic Impact on the UK of a Disruption to GNSS.”   The LE study provides an estimated $1.32B loss per day of a 5 day disruption to GPS/GNSS.   LE utilized a combination of desk-based research and a program of 35 expert consultations, the report identifies patterns of current usage, the functional role of GNSS within each system, resilience (if any) to disruption, and estimates the likely impact of a disruption to GNSS signal availability for up to five days across ten application domains in the UK: Road, Rail, Aviation, Maritime, Food, Emergency and Justice Services, Surveying, Location-Based Services (LBS), Other Infrastructure, and Other Applications.

Specifically, Satelles was mentioned as follows:

“The most applicable mitigation strategies for the largest number of applications are eLoran and Satelles Time and Location (STL)… The cost of resurrecting (e)Loran to a usable level of three masts would be in the order of £50m over 15 years. The cost of STL is unclear at this early stage in its development.”
Link to Full Report