well, we know what happened to the announced tax for tourists which was scrapped after major opposition. And aside from the announcement of one government official who talked about taxing global income a few months ago it has been suspiciously quiet. The only thing that we know now is that 2023 income - not savings - will be taxable. Beyond this point it is all speculation and as it is always the way in Thailand things can change from one moment to another. And I doubt that Thailand is willing to kill its tax base. I understand your concern, though but I would not panic.
When you use VIP lane at Suvarnabhumi airport there are four counters and no real distinction between Thai or foreigners. It is my understanding that the long term visa holder refers to the 5,10 or 15 year visa and not the annually renewable non-O visa (even though it is technically a long term visa). The only way to find out is to try though.