Bitcoin is Finite no matter how long it takes bitcoin will eventually ran out one day but before that happens a new cryptocurrency will probably emerge that will be able to replace bitcoin. it may not be as good as bitcoin but it will be the one who continue the Bitcoin legacy.
Amused with all the responses here, if you really think that bitcoin will eventually be replaced by another coin then no one in the right might out would invest in anything that will eventually run out 
. Bitcoin is here to stay and nothing is going to replace it and it will not run out of coins, in the beginning some people lost their coins because they were not serious about storing the keys as it has no valuation and that is not the situation now.