Do we actually need a battery in every day life that will last millennia?

I mean if a batter lasts 10 years, it’s going to be completely out of date by that time and we will have batteries that are the same weight and size but hold 10 times the charge.

It’s the same as fusion energy. Now we have solar and wind, by the time it’s successfully built, it will be completely useless. Useful only for a few very limited use cases,