I don't see anything happening to the PGA Championship or its stature. Its future is bright as one of the four majors, and I don't believe it will ever change.
Yes, golf is expanding to the pacific portion of Asia and other parts of the world. I just don't see that as a reason to move a major there. You're talking about an event that has tremendous history and has enjoyed major status for most of our entire lives. That isn't something that can be turned off, especially because major status is not given and taken away by anybody or any entity. As someone said, it's a measuring stick for all golfers who have played in the last 80 or so years.
Current players recognize it as a major. Did you see how Rory reacted as he walked off the 18th green at Kiawah? That was the reaction of a guy who just won his second major. He didn't act like that when he won the Honda Classic.
Newer events, "world" events, and the like can attract all the big players and offer huge purses, but they will never supplant the PGA as a major. Just look at The Players. For 30 years people have said it would be the 5th major. It offers a huge purse. Yet it has not become a major, and I don't believe it ever will.
Players recognize four majors, the public and media recognize four majors, and if you want to compare your record to the best you compare your record in the four majors to everyone else's record in the four majors. That is so ingrained as the way it is, I don't see it changing.
And for the record, as I said in another thread, I like the PGA and the courses it goes to (not all courses, obviously...I don't like all US Open courses either). What's wrong with Oak Hill, Oakland Hills, Baltusrol, Southern Hills, or Medinah? What's wrong with Kiawah Island, Hazeltine, or even Valhalla? Yes, Valhalla isn't the best course in the world, but if the PGA can go there and produce one of the most exciting events ever (2000), and everyone can recognize that a major was played there, then that championship is healthy and going nowhere.