The Hamptons may be awash in glitzy decadence, but until recently they were notably free of ritzy rehabs. That’s about to change. Just under a year ago, businessman and recovering addict Joe McKinsey opened an opulent mansion called The Dunes in East Hampton. Spread out over four lush acres, The Dunes bills itself as “the very first luxury rehab center in the Northeast,” offering a pool, jacuzzi, personal trainers, Tibetan meditation, a tennis court and “exquisite cuisine” to “affluent, private-pay patients.” A month costs $45,000. One more and it’ll be a trend. And why not? Malibu, another coastal center of affluence, is home to no fewer than 36 facilities, cleaning up addicts in varying degrees of luxury. In fact, so many sober livings have opened up in Malibu over the past decade that authorities declared a moratorium on any new ones, partly because of complaints from neighbors worried about the impact of “transient” populations. Will the Hamptons’ notoriously territorial socialites offer similar resistance?