I spoke to a Vang Vieng bar owner on a visit to Vientiane the other day. She mentioned that there has been a police clampdown on the bars and hours over the last 6 weeks. Many of the slides have gone and the bars have been strictly told that the music must cease by 6.00pm every evening.
Apparently these regulations have been enforced, however it remains to be seen for how long. It might have something to do with the fact that at least 6 tubers have died this season.