I think it’s fair to say we won’t survive if the sun goes out, unless we move to another planet around another star where we can get the heat and light that we need to sustain life!
The good news is that the sun isn’t going to suddenly ‘go out’, at least it won’t change much from how it is now for another 5 billions years or so… which is plenty of time in the future so we don’t need to worry about it!
If the sun went out, we’d not be able to survive I don’t think. At the bottom of the food chain are plants and bacteria that need sunlight to photosynthesise, grow, and produce oxygen for us to breathe – with no light, they would all die – we’d run out of food and oxygen pretty fast.
Luckily our sun can’t be put out – nuclear reactions in our sun will continue providing warmth and light to us for billions of years yet!
We’d have 8 minutes notice before we knew the Sun had gone out because it takes 8 minutes for light to go from the Sun to us.
If we didn’t have a Sun I’m not sure how we could survive. Maybe we could make a fake one? Or live underground? But plants need the Sun and we need plants. Hm. Maybe we could evolve to not need the Sun?