Infinity is a long time

It will last untill it's replaced by something better.
Just like fiat and gold is being replaced by crypto in these years. The only reason it hasn't happened yet, is because governments are trying to prevent it.
Infinity is just a concept,,, and 100 years for us many will not even be alive so 100 or 1000 years makes no difference in the concept of infinity, which makes it perfectly valid for now to say Bitcoin has lifespan of infinity.
But so many things happen in tech in 10 or 20 years,,, we would have to adjust this thinking in another 10 years.