if btc fails ltc will take over beacuse its the second most old one
It isn't the second most old one whatsoever.
At least it is the second most oldest that succeed.
There were altcoins that came out before Litecoin... "That succeed", in what world?
But LTC has only that it is "the old one" and a lot of people invest money on it. For example DRK has many more features and overtaken LTC.