With recent plans to get into the DEX aggregation business, MetaMask will bring massive value to the whole ecosystem. Currently, decentralized swaps would only be possible for ETH tokens. But with native integration of renprotocol (renproject.io), MetaMask could allow users to directly swap, for example, Bitcoin.
How would this work?
When a MetaMask user wants to swap, for example, BTC to LINK, MetaMask would mint an ERC20 representation of BTC called renBTC. This renBTC can then be used by the planned DEX aggregation mechanism to swap for LINK. The user will never directly see renBTC which greatly enhances UX.
BTC => renBTC => LINK
When a MetaMask user wants to swap, for example, LINK to BTC, MetaMask would swap the LINK for renBTC and let the user specify a withdrawal BTC address. After the completion of the swap, the BTC are directly sent to the BTC address the user has specified.
LINK => renBTC => BTC
The same mechanism can be used for any asset which is supported by renprotocol. Also, renprotocol provides great libraries to integrate and straight forward documentation (https://renproject.io/developers).