Dream on.

Comparing Mimblewimble to the protocol-native articulated logic tiers of the Dash network is like pretending that pigs can fly if they produce enough fart-gas. If Bitcoin implements Mimblewimble as anything other than a side chain it will be an alt-coin.

Bitcoin is what it is and fungibility will be provided by the Lightning Network - i.e. to stay fungible you simply don't transact on the main chain. As for Litecoin, its value offering derives from serving as monopoly money for the founder's brother at one end of the planet and his employer at the other.

Be his guest by all means