If Rep John Mica (R-FL) has anything to say about it, the regulating will be left to the ICAO. He introduced an amendment to His own FAA Re-Authorization Bill that expressly prohibits the FAA from issuing any regs that are "more stringent" than the ICAO. H.R. 658 SEC. 814.
"....Mica rejected Democratic fears of increased fire hazards, and said failing to limit the FAA on this issue could be costly for companies.
"If we didn't have this provision in there, there's be a $1.1 billion dollar impact on industry," he said. 'This is a good provision. It needs to be in the bill.'"
Lithium battery air transport a point of contention in FAA debate - The Hill's Floor Action
Glad to know where his loyalty lies. The UPS F/O was his own constituent and this Amendment was put into the bill after the crash.
This prohibition is not in the Senate version of the bill.