We Never Know
No Slack
Do you conflate that with a total life expectancy of 10 billion years? All I can find is that there are about 5 billion years left (which gives a total life expectancy of 10 billion together with the 5 that the sun already existed)?
Depends on who you ask.
"Astronomers estimate that the sun has about 7 billion to 8 billion years left before it sputters out and dies. One way or another, humanity may well be long gone by then"
Will the Sun Ever Burn Out?
"The Sun is about 4.6 billion years old – gauged on the age of other objects in the Solar System that formed around the same time. Based on observations of other stars, astronomers predict it will reach the end of its life in about another 10 billion years."
Scientists Figured Out When And How Our Sun Will Die, And It Will Be Epic : ScienceAlert