No doubt our resident prophet of doom will be along, appending links to proposals which are not legislated.
IMO there is a lot of detail yet to be worked out in the Thai tax system. For example, I could draw down on the capital of my investments and cash on deposit in Australia, bank the pension I get in Australia, and there would be nothing the RD could lay claim to.
I intend to get a Thai tax number from the Revenue Department. However, whether I actually am required to have one by Immigration, or need to put in a tax return if I am only remitting savings, are unknowns at present.