This proposal begins the migration of legacy cToken contracts to the latest cToken contracts used by the protocol, starting with the WBTC market.

The next-generation cTokens have two years of development & feature advantages over their immutable counterparts. Standardizing the protocol to use the latest cTokens will reduce "tech debt" and allow us to roll out new features to all markets.

WBTC was chosen as the first market to upgrade because of its recent proposal, which highlighted the need to be able to de-risk the market with new features (like supply caps, and protocol liquidation fees). After this migration, the community can proceed with upgrading BAT, ZRX, USDC, and finally ETH.

Upgrade Process

A new WBTC cToken has been deployed, using the latest upgradable cToken contract and implementation. This proposal supports the new market, then switches the COMP Distribution from the prior market, to the new market. The market then inherits a 65% Collateral Factor, to match the legacy market.

The new WBTC cToken uses a modern interest rate model, that governance can update the parameters for. Initially, the parameters are set to an inflection point at 80% utilization, and a maximum interest rate of 40%, which resembles the legacy market.

The two WBTC markets will run in parallel, with users incentivized (but not required) to begin using the new contracts. When the legacy market is small enough, it can be deprectated like SAI and REP.

Contracts

The new cWBTC contract, and its implementation, rely on existing cToken contracts; no code was modified for this proposal, though new contracts were deployed, and peer reviewed.

Discussion: comp.xyz