Whether it lasts forever or not will depend on demand, it will not last if people's demand for it is no longer there. It is true that bitcoin is proving itself to be a superior asset, financial instrument and seems to have no limits and no other asset can compare at the present time.  But as we all know, the world is constantly evolving and bitcoin is just a result of that evolution. So if in the future, when something newer and better is created, the demand for it will probably disappear . So I don't think bitcoin will last forever .

Also, everything has a limit and it's just that bitcoin hasn't reached its limit yet, it's not infinite.