Everyone applies and gets approval for an additional 30, for the most part, to add to your original 45 visa exempt for a US person who comes into Thailand. (The new 45 days from October 1st onwards for six months)
It's up to the particular Office. There is usually an announcement closer to program expiration. Nobody knows but last year when the program was expiring they had planned to ensure STV folks get their 270 days so I would think you'll be fine but once again, nobody knows.