True, but with a constant 100% plus generation from renewable, there obviously wouldn't be any fossil fuel burned to generate electricity. Here we are already at 80% of our total yearly electricity generated by renewables.
When that reaches 100%, it can be done by utilizing surplus at peaks to generate hydrogen, exactly to completely prevent any use of fossil fuels.

I don’t see the whole worlds energy consumption going purely green within the next 100 years.

100 years is a very long time, back in the 70's it was considered a lofty goal to achieve even 10%, and now we are at 80!!
I don't think you have historical perspective.
Personally I think within another decade we will surpass 100% here, and have the ability to export a lot of surplus renewable energy.
I was also mostly thinking about civilized countries, not so much for instance USA.