Will there be Thai Translations in the future, including the User Interface? 

Unlikely, but not impossible.
In general, I plan to finish the game first, and then have someone correct and improve all of the english dialogs, before I start translations for the game. Since the game is still in development, dialogs are constantly added or changed, I think it'll work better for me to translate all text once it's done rather than during the development. Taking care of translations would also take away time from the development of new content, since I would have to work with the translators to get everything done properly.
Thai wasn't really on my list for future translations, but if there are enough thai players, or people willing to help with the translations, it's not impossible to get added as well. I'll probably make a poll for what languagues people want translations for, once we get to that stage, so that I'll know what the highest priorities and demands are.