I'm glad to see several folks here counteract the assumption that 55+ communities are all 70+ folks. That hasn't been our experience either.
We have plenty of older folks in our neighborhood - but they are very active, and you don't really notice that they are "old". Ours is a "winter Texan" community, and I think that already provides a filter, because less able folks don't relocate twice a year.
And many of the newer folks buying in are in their 50s and early 60s, so the average age is dropping. Now we are older ourselves, so the folks coming in are our age.
Well, I thought I was retired. But it seems that now I'm working as a travel agent instead!