Although Part 61 will be implemented in January, there will be a phase in period, and those pilots who are already training using the current system will be able to continue, including writing the current exams.
The same will go for pilots operating over 5700 kgs without an ATPL. They will be given a certain time period in which to complete their ATP whereafter they will lose the right to operate left seat if they have not obtained the ATPL.