Where do I start? Father possibly has Huntington's. Lives alone on opposite side of country from family.

I'm sorry for this distressing situation. Long-distance caregiving is challenging but not impossible. I agree with Funkygrandma59 that, even though your suspicions of the final diagnosis are probably correct, wait for it to formally come from his own physician. After that, if I were in your shoes (and if I were able to do it) I would tell your dad you'd like to come see him to help him get helps and resources into place and generally "figure stuff out". Maybe you won't agree with his order of things to do, but your best strategy will be to let him continue to be in control of some of his life. The minute anyone shows up and starts yanking his independence from him suddenly, will be the beginning of a harder caregiving effort than necessary and be totally counter productive. Meeting with him in person (for at least a week or 2) will give you a chance to see attorneys, social workers, doctors, with him. I think you can lay out before him the different pathways of his choices. For example: if he wisely designates a durable PoA (for medical and financial) then this makes managing those affairs much easier, especially from a distance. The financial PoA will most likely be required to show up in person with your dad at the bank as they often have their own PoA paperwork and process. His MPoA should also be his Medical Representative (a HIPAA form that he will fill out at every doctor's office which will enable his medical team to discuss his private info with the MR even if he, your father, is not present. This is also important to long distance caregiving. You should also gently suggest that you go see an elder law attorney/estate planner and/or Medicaid planner, as care is VERY expensive and most states don't provide benefits until a person needs LTC or MC. IL and AL will not be paid by Medicaid, and neither will much in-home county-funded care. This is a reality he needs to understand. Private pay care starts at $15 p/hr and many have a minimum amount of hours per week. Lots of good care can be had with wise planning. The other pathway is if he remains in denial and does not appoint a PoA. This will eventually necessitate "someone" pursuing guardianship/conservatorship of him. For his family this would be very expensive and time consuming and emotionally wrenching. If it is not possible for the family to do become his guardian, he will then become a ward of the county. In the U.S. no one can have their affairs managed without a legal representative. Then, the county manages all his affairs and the family has no more involvement or transparency into his finances or medical care. You won't be able to take over no matter how much he wants you to do it. Most likely he will go into a county-run Medicaid facility once he cannot take care of his ADLs on his own. So, you can ask him which pathway he thinks will be in his (and his family's) best interests. He may pick "B", which would be very sad, but at least he was informed and you won't ever feel like you didn't do enough to head off the train wreck. I had to do this with my Step FIL, who was a jerk in our family. He was a nere'do well and money sucker who barely worked a day in his life. He got Parkinsons and basically expected us to be his caregiving plan. I told him the options (that I outlined above). He chose B and we allowed him to have B. We couldn't understand his decision but he had all his faculties and we chose to put up a boundary so that his last act in life would NOT be to jerk us around like he did all the years prior. Sounds harsh but I really don't know what any other option would be. You and your siblings should not be "assumed" into the caregiving role without your consent or resources. No one is obligated to care for your father when he had his whole life to plan for his aging years. You are concerned for your dad and no one should judge you for that. But, both you and he must go into this next phase of his life with eyes wide open. Wishing you much success

My in-laws moved to Fla at the age of 68. She had just got over surgery for a heart valve (done the old way) and him, lung cancer but she had to move to Fla, 900 miles away. A 2 day drive for us. FILs cancer came back and he died at the age of 71. From then on we would here, "you should move down here". My husband would ignore her I told her No. I was not leaving my Mom and uprooting my girls. My DHs attitude, she wanted to move there, she wants to stay there, thats her decision but he didn't want to live there.

This was Dads decision. Being that it runs in families, he should have been tested when his cousin contracted it. You and your children should be tested. This is a very debilitating desease. An AL is eventually not going to be able to care for him. He will need skilled nursing.

Medicare does not pay for Caregivers. Its a health insurance. It will pay for walkers, wheelchairs, hospital beds but not aides. I just read where someone can live with it from 10 to 30 yrs.

If Dad does not have any assets to pay for inhome care, he maybe able to get Medicaid to help. He will probably need LTC and if no assets, Medicaid can be applied for.

The worst thing Dad did was move away from family. This is going to be hard to do from a distance. Maybe he should move back to be closer to family. Not saying you need to do his care or pay for it. But it will be easier to find him resources. He should get all his ducks in a row. POA, DNR eventually, Will.

Why don't you wait to see what the tests say as to whether or not your dad has Huntington's Disease, before you start panicking?
And even if he does end up having it, none of you children are responsible for his care. Your dad will then have to see what's available in his area for the care he may require, and if need be he may have to move himself into an assisted living facility, where he will have the staff looking out for him.
Your dad made the decision to move across the country from his family after his divorce, so there really isn't much you can do at this point. Are any of you dads POA? If not, your hands are tied and until he lists one of you as his POA, there is nothing you can do, except wait for the next crisis to arrive. Perhaps then you can step in to try and help.
You are sweet to want to help him, but unfortunately your hands may be tied right now. Wishing you and your dad the best.