If her name is still on the deed, she's still part owner.
This. He can will his part to the new wife, but then the two of them will have to sort it out.
My dad's father had inherited all 'parts' of his family's farm land from previously deceased siblings. He'd taken care of the last four sisters who never married and so it was all supposed to go to him and then to his kids. The last sister died and they found out she'd changed her will to give her part to the distant cousin who had been a home healthcare provider for her. They had to sell it all because this cousin was a crook.
Divorce is never cut and dry. Dad would've had to buy out the ex-wife and then the deed would definitely not have her name on it.
My grandparents owned land together when they separated and divorced. It all went back to my g-ma when he died, even though he'd remarried, because that's how they'd meant for it to be.
This.
