In my oppinion the conditions will change a lot in the future for new applicants, as it is another pretty ill-thought out visa again. But this time in our favor.
Yet for people that allready habe the visa nothing should change and everybody should be happy who got it đ
If you want to do business within Thailand you will have to go though the process for a marriage visa which "comes with" a work permit (that you will need)
I agree with you, DTV holders will most likely not be caught up in the Thai tax system.
The problem in this case are German work and tax laws, as a employee working abroad permanently is establishing a so called "BetriebsstÀtte" (like a foreign branch of the company). That has a lot of awefull tax and social security consequences for the employer himself (not necessarily the employee). Most German employers limit remote work therefore.
All tax and social security rules of Thailand apply to your employer, if you stay there longer than 186 days. He is responsible to comply to every rule. So most employers limit remote work to EU countries. As a freelancer it's your own duty to follow the law, the client just pays the bills you send.