The energy transition for a net-zero future will require deep decarbonisation that hydrogen is uniquely positioned to facilitate. This technoeconomic study considers renewable hydrogen production, transmission and storage for energy networks using the National Electricity Market (NEM) region of Eastern Australia as a case study. Plausible growth projections are developed to meet domestic demands for gas out to 2040 based on industry commitments and scalable technology deployment. Analysis using the discounted cash flow technique is performed to determine possible levelised cost figures for key processes out to 2050. Variables include geographic limitations, growth rates and capacity factors to minimise abatement costs compared to business-as-usual natural gas forecasts. The study provides an optimistic outlook considering renewable power-to-X opportunities for blending, replacement and gas-to-power to show viable pathways for the gas transition to green hydrogen. Blending is achievable with modest (3%) green premiums this decade, and substitution for natural gas combustion in the long-term is likely to represent an abatement cost of AUD 18/tCO2-e including transmission and storage.