The land would go to the next in line of inheritance so it would depend on a number of factors. Your eldest son is the most likely candidate but if you were childless it could pass to a sibling or even a cousin. In very rare cases you might try and pass your lands to the Order itself but that wouldn't be normal. I'd have to dig through my references to refresh my memory to provide more of an answer, unfortunately, and I don't have time to do that now. If I have time later I'll try and provide more of an answer, sorry!