whats also becoming more and more documented is their kids are moving back to the suburbs.
The argument isn't so much that people aren't moving to suburbs, but more that those over 65 are increasing their share of the total populace in the suburbs (and rural areas). Urban areas are getting older as well, but not at the same rate as suburban and rural areas
[1]. It's not a massive difference, but it's growing.
The main thing to keep in mind, is that it's easier to be more dependent on your community in more tightly-packed areas (even trailer parks satisfy this need). You see more people on a regular basis; assuming you aren't a total hermit, you may get to know some of these people, and they can give you hand every now and then. Things like a ride to the doctor, or help crossing the street; help with groceries, etc. This is where suburban living gets more difficult for older generations. Such things may seem foreign to suburbanites who are used to uber-private lifestyles, but it's not unusual in urban areas, where getting help from strangers is fairly commonplace. I live across from a retirement home (bad idea if you hate sirens!), and regularly help the seniors across the street (no marked crossings so they're quite cautious).
With lifespans growing (for most US demographics) -- and the fact that a large number of these folks moved to the 'burbs in the pre-'73 years when gas was under a half-buck/gallon (and a 3-bedroom house outside coastal areas could be gotten for about $35-40K or less) -- the number of seniors "stuck" in the outlying areas will only increase. If their residence is fully paid and amortized, fixed-income folks have little incentive to move to denser areas despite the relative lack of amenities, including health care, since housing near city cores (even in "secondary" cities such as Reno, Boise, and Spokane) is priced to reflect the proximity of amenities. I suppose seniors (and technically I'm one of them!) in outlying areas would need to regularly assess their living and health situations and make provisions to accommodate their particular requirements while avoiding things that place them at risk as much as is feasible. Even though I live in a dense area (and with a RN), those are considerations undertaken on a regular basis (she does nag me about lifting heavy objects, which I must occasionally do as part of my business, because I have a problematic knee: displaced cartilage, courtesy of a sports accident in my youth). But I'm one of the lucky ones -- about to turn 70 with a decent portion of my health intact. And I have no illusions about being taken care of by my offspring -- my only child, my daughter, lives in the West Village (NYC) and has never owned a car in her life!
Bottom line -- there's not a lot that can be done about the distribution of the senior population -- and the general population of the suburbs largely mirrors that situation -- often the consideration of relocating to a denser area is thwarted by not only the prospect of trading space for convenience and/or safety, but also the likelihood that it might not be as simple as that equation -- the differences are arguably not linear in nature, with the more desirable neighborhoods affected in terms of price by ongoing gentrification -- so even finding anything affordable becomes a quixotic quest. At this point, a real & viable solution has yet to emerge.
No doubt that moving to more urban areas can be expensive. But that's why you have urban planners doing their best to ensure that we build more densely in the first place, and work with subsidized housing organizations to maintain a supply of well-built affordable housing close to public transit and other places that can be accessed on foot (especially helpful for older people who may not be able to afford a car, or who may be blind and unable to drive). This is happening somewhat successfully in some cities (Tacoma), but not as much in some others (San Francisco, from what I can tell). But a lot of west-coast cities have also seen massive population booms over the last twenty years or longer, which has been leapfrogging the pace of development.
My grandparents are both in their late 70s; one turns 80 in two weeks. Both are doing fairly well, but have given up on good portions of their 12-acre suburban property because it takes them longer to maintain the important areas directly adjacent to their home. Bad knees, bad backs, and other injuries are slowing them down, and forcing them to be more cautious. Neither has any life-alert system, but may need to consider that in the future. In the meantime, I've begun volunteering to help them with various yard-work projects, but I don't have much additional time to devote to this; they are well-aware that moving somewhere more urban (a genuine fear of my grandmother, who loves the country) will eventually become a necessity, because it's simply not practical to live where they are now, given the amount of effort required by themselves and others to keep the place running. They are more of an edge case, but old people in general have a harder time with basic maintenance (ladders, mowing, etc).