Natural gas infrastructure already deals with hydrogen: 2% of natural gas is hydrogen. For town gas which was used before (made from coal), hydrogen content was around 50%, so this isn't entirely new. Of course you can't re-use the existing infrastructure and use 100% hydrogen.
This isn't black-and-white. Leakage is a disadvantage, as it is for fossil fuels (natural gas, oil, coal,...). Other technologies have other problems: windmills kill birds and bats! Pumped storage kills fish! Dams cause methane leaks! It is important to quantify how much of a problem those disadvantages really are.
