What Will Happen to the Sun in Seven Billion Years?

In seven billion years the sun will finally run out of hydrogen fuel, and the core will be left with helium at which point the sun will collapse because no new heat is being produced in the core. If people are still here on the earth orbiting the sun they might decide to do something about that - but you can't guess what would happen billions of years from now. The only way to get around this to be scientific is to say, assuming no human intervenes, then the sun will expand into a red giant in approximately 7 billion years. But until then, bye-bye.