See I would think it would be the other way around. That 65+ folks would move to the suburbs where its quieter and higher income (100K+) millenials would flock to the city centers so they can be near the restaurants, theatres, museums, and eateries to meet up with their Hinge/Bumble/Tinder dates.
Medical Centers.....Doctors......no home/lawn maintenance......no school age children running around........
The burgeoning upper middle-to-wealthy 65+ demographic worked hard and invested all their lives to afford pampering, entertainment and service.
In my and my colleagues advisory practices throughout the financial planning industry, we are seeing newly retired/empty nest clients moving to condos/apartments. Less than 10% move to single unit housing. Once society starts adapting driverless pod technology in urban centers, the ease of urban lifestyle for the older upper middle class set will become even more pronounced.
Those numbers may very well be different for economic classes below upper-middle class (i.e. those who don't hire financial planners).
Compounding this is the very stark and growing economic disparity between those who are comfortably retired (with 20-30 years of extended life expectancy) and those in today's workforce being squeezed between lower real wages/benefits and longer work hours. This will become a larger social rift with all the implications going forward. Long story short, the demand for urban towers populated by semi to wealthy retirees will push younger workers out to the cheaper burbs (and will increase generational resentment).