There's a grand Prix in Singapore - going to be very hard to get them to bring a race to Thailand due to that proximity. When Malaysia couldn't financially do it anymore, it went to Singapore. Singapore are not going to give it up.
Whilst there is a bidding process to get a grand prix, you have to have high class 5 star facilities, an infrustructure in place for visitors and delegations. I can't see them allowing a grand prix where the moment you set foot of a plane a taxi driver will rip you off.