Between Litecoin and Dodge as a replacement for BItcoin if BItcoin runs into trouble, I would pick Doge. The reason Doge has a tail emission. The biggest challenge facing Bitcoin today is the 1 MB blocksize limit. What many do not realize is that the reason why there is so much division among the Bitcoin developers is that there is no simple solution to this problem. Simply increasing the blocksize only kicks the can down the road. The issue is how do you secure Bitcoin once the block subsidy runs out? This is why many are so reluctant to increase the blocksize in order to make the blocksize a scarce commodity to ensure that there are enough transaction fees to secure the network.

The one existing solution for an adaptive blocksize in POW coins is in the Cryptonote coins. This solution works by applying a penalty function to the block subsidy; however this requires a block subsidy to penalize. With the Cryptonote adaptive blocksize and without a tail emission (say Bytecoin) the blocksize becomes effectively infinite when the emission runs out and there is no way to secure the coin. It is for this reason that Monero has a tail emission, making it the highest capitalization POW coin to have solved the Bitcoin blocksize issue. Doge has a partial solution since it has a tail emission in place. Adding an adaptive blocksize is not a disrupting hard fork but changing the overall maximum number of coins from finite to potentially infinite is. For this reason my choices for likely replacement are: 1) Monero 2) Doge.