Deciding on the residence can be tricky and a lot of other country do not consider only where you are living but also your family for instance. For example, we explain in our FAQ how the French government determine whether you are a French resident.
Any change will have to be foreseen with all international tax agreements between UK and other countries, including the EU regulations.
This is apparently only a project and we will have to know more before we are able to judge on the impacts.