I'm not sure where Thailand would fit into the current F1 calendar, especially in 2027. Earliest contracts ending are for Singapore and Mexico end in 2028, Japan 2029 and Brazil, Abu Dhabi, Saudi Arabia, Austria and China in 2030. Mexico may/may not renew as Checo is currently no longer driving in F1. The teams and drivers already think the season is too long, so adding another race might be wishful thinking