I don't know when this would happen - it'd be a big deal, like a fork I think. The point is on Ethereum we might create an ERC-20 token for NewCoin that wraps it and then all of our interactions with NewCoin is via smart contracts. On Cardano these would be native to the chain in the same way as Ether is on Ethereum (or Ada on Cardano). If you need a layer of logic over the token you'd need to introduce a smart contract but for things like transferring, getting supply, etc, it's the same as doing that for Ether on Ethereum - they're essentially primitive functions on the chain.
