After 30 years of marriage in Michigan a widow the found majority of assets TOD to his daughter (not hers). Will this be unwound in probate or stand? No will.

Accounts that are titled as payable on death (or transferable on death) pass to the named party outside of probate. In general, yes it will stand - the only caveat is if the estate owes any estate tax, in which case it may be possible to attach some of the TOD assets to help pay the tax bill. As for the remaining asets - the widow and the decendants' surviving spouse split the remaining assets in accordance with MI's law, which I believe grants the first $150K to the widow and splits the remainder (if any) in half between the widow and his child(ren).