Parameters in the cauldrons can't be changed once deployed therefore, in order to change them, new markets will be added with updated parameters, and the previous one are deprecated.
You can find all Markets, even deprecated ones, in the "Markets" page of this wiki.
When a Cauldron is deprecated it only means that no more MIM replenishes will happen. The cauldron itself is still fully operational, and if a users has an open position it can still be repaid at their own pace and time!
Bear in mind that if you had a position open in a deprecated market, your collateral won't be showing up in the new market.