Your code will open up the WiFi setting page, and from there one eventually should be able to reach the WiFi Direct page. I've found that navigating from WiFi page to WiFi Direct is not uniform and confusing; different manufacturers have different way of doing it.
I was hoping to open the WiFi Direct setting page directly to save a lot of troubles for the app users; if such intent doesn't exist, then I'll use your code.
Thank for your help!