DH is planning to talk to his boss tomorrow about quitting/dropping down to two days/week. If his boss isn't available, the conversation will get punted to next week.
We're fairly certain we're going to just have the two of us alternate days if he does go part time. With DS's preschool and DD starting kindergarten, we only need about five hours of childcare two days a week, so holding onto the nanny who would need to be paid a minimum of 8 hours/day just seems silly. We feel badly to let her go given her husband's illness, but we'll give plenty of notice so she can find something else before she stops working for us. We've gone back and forth on this a ton, but this is where we've landed.