There were many threads earlier regarding this topic, first it will take a long time for all the coins to get mined and second important factor is that the price would be so high and we need a better solution to counter the price when it comes to transaction charges, bigger blocks was one solution but the question remains how big the blocks can be and whether we can have a better solution than we have now to balance everything. Even now the miners will be earning a few extra bitcoins apart from 12.5 bitcoin they earn with every block and by that time the price will be that high that they will compensation with the transaction fees alone.