Respect for Marriage Act prevails. Existing are still valid (at least federally) and states must offer full faith and credit to marriages that are valid in the state in which they were performed. So WI’s ban will mean no new marriages here but WI will have to recognize them from IL and elsewhere.
Similar issues to abortion state law applies except they have to honor the contract from another. Didn't we go thru this nonsense before?
And ours is a constitutional ban and our current legislature will never start the process to overturn, but at least two border states will keep it legal for the foreseeable future. Not ideal, but better than nothing.