Green hydrogen will be cheaper than petrol. The goal is to make it from curtailed renewable energy which will cost <$0.02/kWh. You can't go around talking about cheap solar and not realize it means cheap hydrogen too.

It will be a significant fraction of the year that will be powered by hydrogen as the primary energy source. Just creating more green electricity will mostly end up wasting it as there is no other way of capturing and storing it.

All regions must have hydrogen available. For things like industry, shipping, trucking, grid energy storage, etc., it is basically unavoidable for a country to not hydrogen. BEV islands will be small and not an alternative to widespread deployment of hydrogen-related infrastructure. But the reverse is not true, as it is fully possible for a country to reach zero emissions with no BEVs.

The biggest change in environmental policy is the widespread deployment of hydrogen and related technologies. Many countries now like the UK, Germany, Australia, Japan, etc., have very significant hydrogen expansion policies. These policies will accelerate rapidly going forward.