Technically, this function already exists as a SWAP.BTC <--> SWAP.HIVE utility on the Hive-Engine. I am presuming you are saying they wish to make BTC a Layer 1 asset and swap directly at this layer? I am not sure I would be so enthusiastic about such a mechanism, as it would expose the Layer 1 of Hive to BTCs designed volatility. Leave it as a Layer 2 swap system. It is already a steady top 10 in volume there. If people wish to increase the volume, let it happen there, off the Layer 1 wallet.
SWAP.BTC is centrally issued and controlled. You have to trust the deposits will not get stolen by the provider and will behave correctly. In fact a hack occurred stealing 10s of thousands of dollars happened a few years back resulting in BTC lost. This poses a significant risk to anyone using SWAP.BTC and treating as safe as normal HIVE or native BTC.
SPK aims to build a swapping layer that is fully decentralized and trustless retaining a high level of security through smart contracts and other mechanisms. More details will be released at hivefest in Sept.