http://www.bangkokpost.com/news/sports/1156781/star-boonsaks-exit-exposes-lack-of-backup I wonder what happened to a very promising junior Thammasin Sitthikom who was shining in 2012-2013, he stopped playing in 2015 at the age of 20 only. UPD.: He had a knee surgery in March and considered retirement.
Thai players retire pretty late. That article on Boonsak's retirement says Saralee retired at 37 years old.