I think bitcoin will be around in a 100 years. Gold has been around for thousands of years and fiat money has been around for nearly a century. Bitcoin will be here as long as it survives regulations or any unforeseen technical issues.
Bad comparison though.
As others have said, 100 years? too much to speculate. First, we really don't know what will happen to the planet we live in, for God's sake maybe it won't be inhabitable in the next century.
But assuming people that time survived, maybe they will see the last bitcoin being mined and if become some sort of novelty or collectors item that time or it could be traded and become the currency that we all have been wanting to see, they definitely it will still be here.