So far they have just stated 2015..... but since it's Thailand and it's a hotel opening, who really knows. End of 2015 (or even 2016) wouldn't surprise me as well since they still need to do a lot of work on the exterior before they can even start on the interior.
But I look forward to having another great option as well, even though I'm a fan of the GH Erawan. I'm not so sure any additional money will be worth it, but there hasn't been much in details for the PH yet.
This shows a bit of the height, it's supposed to be 36 floors:
http://www.hotelchatter.com/story/20...ting_Its_Twist