Having worked with the senior population in NYC for the past 6 years I can say that this new trend of seniors relocating back into cities is great. This article over at Next American City discusses how Chicago is actively seeking out seniors. It has been discussed in many circles (and any city that has lost population) just how great it would be to bring these individuals back into our cities.
A transformation is definitely happening but the young have nothing to fear. Seniors are a little more hip these days than in generations past - at least to pop-culture standards. The kids you saw at Woodstock, knee deep in mud and quality marijuana, are now in their sixties. They vote for Clinton, which maybe isn’t as “rock star” as Obama, but at least it’s not as Everly Brothers as John McCain (to be fair to the Arizona senator, his daughter confirms he listens to Lauryn Hill). They’re more connected and less secluded than the generation who moved south to “get away from it all.” What’s the worst that could happen? A sound curfew? Chicago is one of those cities that actually goes to sleep - at 10pm, you won’t find anything open.
I can only see this as a plus as it will provide more diversity in cities. Unlike NYC, many seniors are trapped in rent-regulated apartments and can't afford to leave their apartments and still afford to live in NYC. This is a pretty scary scenario for someone who has lived in the same area for the last 30 years. In my experience seniors keep the city planners in check, they are not afraid to speak out, and yes, they do actually vote.