We really have no NEED to downsize at this point since our house is less than 1800 sq ft and is single level. However, our kids don't live in easy commute range. We have set a goal for ourselves to be "ready" to move by the time I turn 75 in case we need to move near one of the kids for practical purposes. We are decluttering, etc. to make things easier when/if that time comes. I like the idea of selling then and renting somewhere near a beach for a few years before settling near one of the kids, but DH is 5 years younger and probably won't want to give up our house yet at that point..
My parents always said they'd be willing to move near one of us, but by the time it came it felt too hard and they dug their heels in. I spent 5+ years living between two states trying to care for them, had to retire early to do so, etc. We don't want to do that to our children.
Eventually, we'd like to live in a senior leveled care living situation - preferably in an independent apartment, but with help nearby if we need it and the ability to move into leveled care easily as needed. We envision having moved into that type of situation by the time I'm 80 and DH is 75 if we haven't done it yet. Having dealt with my parents AND in-law's homes and properties, we want to have everything scaled down to make things easier for the kids. DH's parents needed a lot of help already in their 70's and mine did in their 80's and into their 90's so we're preparing with those possibilities in mind.
By the time my mom passed, Dad had passed and she had moved near me and I had already emptied, cleaned up, and sold their home. Experiencing her passing that way was so much less traumatic for me as their primary caretaker. I already had photos digitized, etc. and had made the basic decisions of where stuff would go. She was 93, so it wasn't exactly a surprise that she was going to die someday. At some point you have to be practical. We want to be practical early and set ourselves (and our kids) up for an easier transition.