We go through a period of time when somebody asked about your parents you say "Oh, dad's doing great. He's playing golf. Mom's doing great, she's playing tennis. They're traveling, everything's going wonderful."
Then the next stage is- "They're not doing as well." There's not a crisis but when somebody ask you about that- "Well you know he plays golf once a week now" and you maybe joke about "Yeah I rode with Dad the other day. Boy, was that an experience". Or "Mom, you know the house isn't as clean as it used to be."
Don't ignore those things. Those are signs you need to sit down and talk to your parents. Ask them how thing are going. Don't tell them how things are going. Ask them how things are going. It's important for them to stay in charge. They've been in charge for a long long time. There real use to it. Help them stay in charge. You're doing them a huge favor by doing that.
Don't wait for a crisis. When a crisis comes; you're reacting. It's always purely reactionary. You're not having a lot of choices there. If you're talking to your parents up front, you're learning what they want. That's the question you asked them. "What do you want? What do you want to do? Where do you want to go when you can't stay in your home anymore?" You will do them a huge favor by doing that.