That's the constant refrain from the local suburbanites every time there's some story about how some residents actually live in Philadephia without being court ordered to do so, or forced to by the local Sucky Blogger Dictator.
Probably some truth to it! People do change as they get older, and start having different priorities, but this misses the point that one reason more people like living in the urban hellhole more is that the urban hellhole is nicer than it used to be. At least, parts of it are. Some of the hipster yuppie trustifarian slacker food stamp receiving lazy desperate millennials might choose to stick around. Some will not! (I suspect the other thing this misses is that rentals and starter homes in the inner ring suburbs that are declining in number/increasing in price. Factor in cars, commute, and commute time, and that smaller place in the hellhole looks a bit better than that exurban mansion. The life they grew up with is expensive.)
Like The Kids Today in the urban hellhole, these voters will also grow up and have different priorities, though my vast lifelong experience tells me that their politics won't change all that much. My cohort was a big Republican cohort. Republicans were the cool guys back then, and the Democrats the dweebs. That cohort is still pretty Republican.
The Kids Today don't like the Donald. Future versions of those kids probably won't much like the 20 years from now version of Donald, though there's a good chance some of them will.