This would / will still take ages / decades. It could also be that it makes total sense to use 100% solar/wind + battery in everything not city and use fusion

This would / will still take ages / decades. It could also be that it makes total sense to use 100% solar/wind + battery in everything not city and use fusion in city/for cities. I would also argue that the 'no longer needed solar' will then be sold and used everywere else until all poor countries also are using solar energy.