but on the flip side, there might be a significant chunk of the current generation of teenagers who aren't being forcibly subjected to whoever the new Milli Vanilli is. Isn't that some kind of tradeoff?

I'm not sure how to feel about the loss of shared experiences across the entire nation. On the plus side that probably helped us communicate and get along with each other. On the minus side, a lot of those experiences were vacuous and a waste of our mental energy to engage with them and remember them.

It'll make it harder to have a hit show like "I love the 80s" in twenty years, definitely. It'll make it a bit harder to have conversations with random people you meet at work or school or parties. But on the other hand -

1) We still have lots of other shared experiences that aren't musical. American Idol, Jersey Shore (ugh), NFL football, Barack Obama (for or against), Twilight, Harry Potter, etc. It's easy to get caught up exaggerating the increase in splintering when really there are still huge swaths of the population experiencing the same things at least to some extent. (I've never seen or read Twilight, but I know who Bella and Edward and Jacob are, and that werewolves apparently don't like wearing shirts.)

2) We will increasingly look to people with whom we DO share memories and tastes to communicate with. It will be harder to talk to random dude at the gas station, but you might forge tighter bonds with people that have the same fondness as you for grime or whatever else.