For me this statement is a logical conclusion to the thought experiment ”imagine if everyone lived forever”. But I realize maybe for some it isn’t, so lets categorize this as an opinion.
Functionally there'll still be an end-date for most "human" lives.
But there's plenty of meaning to be found in 10,000 or 100,000 years of life, without disease and death lurking around the corner every day.
It will still be lurking around the corner and it will change your risk calculus completely. Today, if you go out and get hit by a bus, at worst, you lost 70 years of your life. In the future, you're risking 10-100k years of your life. What's worse is having to accept this risk for your loved ones.
A better question to consider would be, what would people do if they had only 1/5/10 years to live.