Being honest, I can't guarantee you this is happening, just some rumor, but I would keep a closer eye on it... We may see some more surprises. We already got plenty these days.
The current law is already in effect: if you spend 180 days per calendar year in the country, you become a fiscal resident. Remitted money is taxed, with amounts depending on existing treaties.
When spending 180 days per calendar year in a country, you become a fiscal resident regardless of your nationality or visa status. I highly doubt this speech applies only to Thais, given the increasing number of digital nomads arriving. I would actually expect the opposite.