here in the UK there was the whisper of using the gas system to deliver hydrogen (or a variation). I heard last year that one of the big gas mains in Yorkshire was being converted to supply hydrogen.
I guess if you replace the boiler on the other end with a fuel cell based system that was still 'wet' so the radiators and water heating in the house stayed the same the there may be less change needed?
If the goal is heating, hydrogen combustion would be much cheaper and just as clean. It might not be as efficient as a fuel cell + heat pump combination, but I think the production of fuel cells and heat pumps would have a worse environmental impact than generating the difference in hydrogen.
I guess if you replace the boiler on the other end with a fuel cell based system that was still 'wet' so the radiators and water heating in the house stayed the same the there may be less change needed?