Even if we cure all illnesses and find a way to halt ageing at 25, and we got rid of car accidents (the biggest accidental killer) and suicide (the biggest deliberate killer), the remaining types of accident and homicide would probably still give humans a mean lifespan in the order of a few thousand years — I doubt I’d be bored of life after a mere few thousand years.
Hundreds of thousands of years would be utterly unpredictable given how big the scale change is (fun though the idea of star-lifting is), but a few thousand years is definitely still in the range of learning to master skills that I admire others demonstrating.
Not dying from aging in not the same as being immortal though. You could still die from a car accident for example, and there is of course the option to kill oneself (even if I'd consider that a tragedy.)
This is if biological aging could be _fully_ fixed, the first steps are rather to live a healthier life a bit longer.
I would expect people to live until they got bored.
I don't have the exact number, but without aging, we'd statistically only live until ~1000 on average before getting hit by a bus or choking on a bite of steak.