Batteries have improved over time, but I'm not convinced that they'll see the vast improvements necessary in order for them to replace natural gas for a long time. If natural gas really must be replaced the most logical alternative might be ammonia.

Ammonia has hydrogen's good properties: not a greenhouse gas, doesn't cause smog, numerous production methods including electrolysis, easily transported in liquid form, can be used in fuel cells or in ICEs. However it doesn't embrittle, in liquid form it's actually denser in hydrogen atoms than liquid hydrogen is, and due to its agricultural applications there is already an established distribution infrastructure (in the Midwest, at least).