corset have been part and parcel of the alternative fashion scene for a long, long time.
Goth, steampunk, rockers..etc, corsets, the real steel boned one have been worn by women who dress in modern variations on Victorian clothing. You need only attend Whitby Goth Weekend to see corset wearing is very much alive and well.
All this move into mainstream is about, is the fashion industry deciding, once again, to hijack the alternative fashion scene. It happens every now and again. They've done it with military gear, tie dye, tartan, army boots, leather jackets, skinny jeans, band tshirts (people wearing ramones/motorhead tshirts when they've never even listened to them anyone?)...etc.
I've been part of that scene for a lot of years, as have older friends of mine (now in their 60s) and its something we often talk about, once the scene picks up on a 'fashion' you can pretty much guarantee it will crop up in the mainstream within 2-3 years.