Existing infrastructure is designed for & can be used for hydrocarbons with varying levels of hydrogen in their molecular structure; I don't believe there's an issue there. Most of the H2 in town gas is in the form of hydrocarbons, which are less reactive than pure H2, even if there's a relatively high percentage of H2 in the mix (as the H2 is strongly bound to the carbon). Embrittlement is definitely an issue for more than just storage tanks.