So, after my previous post, a response for OP :
As you can read in the french report this (page 56) : "Finally, the applicability of such a reform would also require tightening the rules for unjustified change of nationality, or to countries with privileged legality in terms of personal tax. This would imply a legal definition of these countries with privileged taxation but also the introduction of a notion of presumed departure for essentially fiscal reasons, accompanied by significant sanctions."
I called a lawyer who help french with big fortune to renounce their french nationality since 15 years. He said it's difficult or impossible in certain case if the government knows you are very rich and/or you are not living outside the country since 10 years minimum.
When I was trying to renounce my french nationality in anonymous way for grabbing informations, one of the questions was "is it for tax reasons ?" even if the citizenship based taxation isn't ready. The second question was "list all your incomes since X years".
So imagine when this new tax will be ready.
If you have another good nationality (for traveling in EU), and if you are sure that Germany has planed this s**t, I deeply recommend you to renounce your nationality before it's too late.