I understand. Many are concerned regarding investment income. Not day jobs. Municipal bond income is tax free in the USA. Not in Thailand. So taxes will be paid on it in Thailand. Up to 35%. The tax treaty agreements do not eliminate the paying of taxes.
It is aimed mainly at very wealthy Thai citizens not paying Thai taxes on earnings in foreign countries and less on Thai labor overseas. Most Thai workers in foreign countries earn relatively small sums of income. The tax code is not going to be rewritten in its entirety. As I understand the wording of two or possibly three paragraphs will be changed. Many Thais from wealthy and upper middle classes are concerned and not only those married to foreigners. Yes time will tell but remember TIT coined by Bernard Trink.