Self-Finance Long-Term Care

I'm 53 and planning to retire in ten years. My husband and I are both current in good health, however, he has one of the genes that makes late-life Alzheimer's more likely, and my parents lived a long time so I expect to live into my nineties and would expect to need some care then. We currently have about $1M almost all in a traditional 401k. At retirement, most of our basic life expenses will be funded with a pension and SS. The portfolio will be used for a new house, travel, help out the kids, and to fund long-term care if needed. What do I do as I get to retirement with the money intended for long-term care funding? Do I leave it in equities and hope I won't need to withdraw from it during a market downturn? Do I put some in bonds? Do I wait and if one of us shows some signs of a health issue or deterioration, move it into a less volatile financial instrument then? What's the best way to be prepared? I don't want to buy LTC insurance – I've read to many articles about it being difficult to get it cover what you actually need.