Except nuclear from fusion not fission will be the primary source in the future. That just needs deuterium and tritium, water and lithium, both of which we have in abundance (though lithium has it's own problems).

However the reason it's important isn't just for the climate crisis now, but for going to get more minerals and water in space eventually. Miniaturized fusion reactors will carry us well beyond the solar system one day.

Coming back to today, the key is storage storage storage storage. Even if we had fusion on the grid tomorrow we'd still need to deal with the demand above baseline at night or when the wind isn't blowing. That requires storage to place excess power during the day and windy days, and use it accordingly.

Eventually, 100-125 years or so in the future, it will mostly be fusion and massive space solar arrays we 3D print and bring the power back down to Earth.