Plastic/FRC pipes solve the leakage problem. They are also salt water resistant. Soft steel NG distribution pipes have low leak rates as well. Converting hard steel NG transmission pipes is possible by lining them in plastic. In any near future, H2 only new pipes would be built. H2 is more valuable when it is pure because it has higher efficiency electric conversion than NG, as well as being an ingredient to several important chemicals.
Corporatist PR slogans and promises is not a path to human sustainability.