Although it is unknown whether third-party banking methods such as PayPal, PayNearMe, FanDuel Play+ card, and the like, will be accepted as withdrawal methods in Michigan, these options are certainly widespread in other legal sports betting markets in the US, and will probably be offered in Michigan at some point in the future. In the meantime, you will be able to use ACH online bank transfers to withdraw your winnings, which will take up to four days to appear in your account.
You will not be able to use credit cards for withdrawals at any time, but you probably will be able to request a check by mail as an alternative method.