MakerDAO plans to set the vault limit at 50 million DAI, with any excess used to buy MKR and add liquidity

ChainCatcher message, the MakerDAO Risk Core Unit team has released a proposal in the community titled "Introduction of Smart Burn Engine and Initial Parameters," which is currently not yet voted on. The proposal states that the Smart Burn Engine is a new type of smart contract system designed to allocate excess Dai from the Surplus buffer that Maker does not use as an emergency reserve. The difference between the Smart Burn Engine and previous burn designs is that MKR tokens will accumulate in the form of Uniswap V2 LP tokens, rather than being acquired and burned. Additionally, Surplus Auctions (Flaps) will be replaced by the Dss Flapper contract.

The Smart Burn Engine will be activated when there are more than 50 million DAI available in the Surplus Buffer for flapper.bump. Once the Smart Burn Engine is deployed and activated, it will regularly use the DAI from the remaining buffer to buy MKR tokens from the Univ2 DAI/MKR market. Then, MKR will be matched with additional DAI from the remaining buffer and provided to the same market.

In return, Maker will receive LP tokens, which will be transferred to a protocol-owned address. This system will increase the on-chain liquidity of MKR over time. Market actions will only occur when the slippage is less than the amount allowed by flapper.want. (Source link)