I doubt that social cliques and house loyalties will ever be as strong as they were in the books.

Maybe, but I see hints in Padma's snobbishness that we should see the usual amount of icyness to those beneath me and prickliness about those who think themselves better than me. Many of the parents (the Malfoys and Lestranges, whom we see directly, and the Patils, Browns, Blacks, Notts, and Strettons, whom we see indirectly) seem acutely tuned to the social pecking order, so I'd be very surprised if their children do not pick up their parents' social biases.