I do not think anything will change as you can read all the comments above, it's earned income that is to be taxed not mandated saving for visa usually made up of foreign pension or savings that has already been taxed. Do you really think that the Thai tax office is going to employ thousands more employees to go through bank accounts and enquire about specific deposits and when it was earned? It would be a shit storm of the highest magnitude. They don't even check on the majority of the population now.
If you have enough time apply for a Non O visa before you fly out and then you won't have much problems here opening a bank account etc, all you will then need is to season your 800k for 2 months before you apply for your yearly extension,